They do get that coating as long as they have been fully ripened. I would lower the humidity by removing covers as soon as I see any molding. Remove patches of the infected seeds quickly, if you do not want mold to spread to healthy seed.

If you harvest seed that has gotten damp after ripening, the gel begins to swell, mold spores find the seed, and embed themselves in the coat and remain active while the seed is redried. Insufficient drying of good seed and especially storing such seed in a closed container that does not breath is a good way to get bad results.

Along with ripe seed falling out as soon as it is ripe, this is what makes salvia seeds so dear, and why few species are seldom available and always in short supply.

Thanks Rich
I most definitely had some storage problems this time. lol
My poor seeds went through a lot during and after our fire that we had in August. I tossed a bag of seeds into my shed for a few months and also had some that rode around in the back of my van from August until January. I thought about tossing all of them and starting over but decided to give them a try.
Rich I took your advice and removed the cover and also put a fan on them for just a little while yesterday and took out the fuzziest seeds. Good news - I found seven this morning that had sprouted so maybe I'll get at least a few seedlings.
What do you store your seeds in that breathes? I usually use ziplock sandwich bags and then put all my little baggies into a larger zip lock bag. My poor abused seeds. I bet I would have better results if I do this right.

Water permeability of plastic bags is low, so I would use paper envelopes. Dry the seed after it has been cleaned (and de-dusted with a fine screen) in a tray one layer thick.

You can clean out the chaff and dust by swirling in a bowl and blowing on it. I would wear safety glasses if you do this, because you do not want any of that chaff or dust in your eye. I once scratched my corneas that way. Remove as much as possible with screens first.

Maybe that's why I've never been successful with s. guaranitica seeds. I don't think there's anything I've tried to grow from seed more times than that without getting a single one. I've done ok with greggi, Yvonne's, darcyi, subrotundra, and coccinea but didn't really have a high rate of success. I hadn't considered that storage could be my problem. If my guaranitica returns this spring, I shall try again. Right now we're getting a lot of rain and I was just thinking about how soggy my yard is and wondering if my salvias are drowning. I need to start planning a raised bed.

Christie--- I too have not been able to germinate s.guaranitica seeds and have given up on those but I do have a container of them winter sowed outside and will see what happens with that. Last year I also had some of that fuzzy mold develope inside my pots once they had grown some. But this year I keep making the byrons famous tea recipe that is listed on this site and spray it on top and also bottom water my flatts. So far I have not had any of the fuzzy stuff and some of my seedlings are up to 4 and 1/2 inches tall. It is said that the tea may help keep away damp off. So far so good.

Steve - Winter sowing worked with my other salvia seeds last year but not with guaranitica. I wasn't able to harvest a lot of seeds though. I WAS winter sowing my darcyi seeds this year but we've had a lot of rainfall and I brought them in so they wouldn't wash away.
I found the info on Byron's famous tea. I've used chamomile tea before for seedlings but don't have any now. It wasn't clear whether regular tea helps as much with damping off and mold.
I could see some more sprouts this morning and they look ok but I'm afraid to leave the lid off the whole time. I don't want them to dry out. I'd like to put them back outside now that the rain has stopped but they were inside for a few days so I don't know if that's going to work. I'll have to acclimate them slowly just in case.
I have some 'Cerro Potosi' seeds that are starting to sprout too. : )

Christie--- I too use the chamomile tea, I dont trust regular for doing what I want. It is also said if you are having that trouble to circulate some air over the plants. I havent done that yet but still havent seen anything to concern me. I read somewhere that moldy stuff that I had last year and what most likely you have will not hurt the plant. I will keep hope on guaranitica wintersow untill nothing happens. Its been too cold here to put plants outside just yet, but plenty of rain. Today I noticed two small blooms open on one of my greggii, what a shock, looks like they survived. I cut those back about a third.