Sometimes, AC condensate drains run outside and into the gutters. If they re-pitched the gutters, this may cause the AC condensate to run back into the pan and overflow. Can't think of any other reason this would do this now.

In any event, you need to get you AC checked to see why the primary and secondary condensate drains are working.

Yes, I was thinking the same, that the re-pitch must have caused it. It also rained last night/this morning, so presumably some of the rainwater ran back into the pan as well. Are the pans something we can easily access ourselves? I don't know where they're located.

We dont have enough info to really help you. This is more of an on site diagnosis. If they somehow got rainwater to backflow then yes that could do it, but I guess I would have to see how it is set up to make a guess on that.

Update: the roofer came back and checked all of the gutters and confirmed that there is no drain pipe outlet into the gutters, but we couldn't figure out where the drain pipe ended up. However, he did find an old downspout tucked away in a weird spot in the soffit, and removed a large clog from that, so I started the AC again just to see if the water would start draining there. It did not, but water did start dripping from another area of the soffit (halfway around the house from the unit!).

Anyway, it was obvious that we weren't going to get any answers without an expert. So I called in an AC guy, who quickly figured out that the drain pipe runs down into the basement (why go all the way from the attic to the basement instead of out into the gutter?), and that it was badly clogged. He blasted out the clog and added a union so we can easily shop vac it ourselves now and again, and all was well. He also installed the overflow emergency switch that the previous owners left sitting (unconnected) in the drip pan. Grrr...

The relationship between the soffit/gutter work and the leak is still a mystery. It could be coincidental, but my guess is that the drainage pipe has been clogged for quite some time, and the only reason we didn't have a major indoor leak before now is because the water was seeping into the soffit and slowly draining through all of the holes that the roofer patched (in addition to some large holes in corners/dormers, he also patched about a million small carpenter bee holes). Regardless, all the water is now going where it belongs, thank goodness! I've got a dehumidifier running in the rooms that got wet, and I'm hoping we can get away with just repainting the ceiling rather than replacing all of the drywall. I do worry about what might be growing inside those soffits, though - the gutter guy said a ton of water and debris came out of the old downspout, so I can only imagine there's more where that came from.

Thanks for your guidance as always!

That's great that you got it fixed and thanks for posting back your results.