Bermuda grass is not the only type of grass that can create these sorts of "weed" problems, although it does have a reputation for being one of the worst. A great many other common turf grass species can display this trait. Turf grasses come in three different growth habits -- clumpers, rhizomatous and stoloniferous -- and most common lawn blends, both warm and cool season grasses, combine a variety of both. Bentgrass, Kentucky blue and creeping ryegrass -- all of which are common to various cool season grass mixtures -- are either rhizomatous or stoloniferous and can create rooting, weedy problems when applied as a mulch to a planting bed. There are a number of other various grass species as well that will create similar issues. Bermuda and Zoisya grass are well known for this problem as well and they tend to be used most often in warmer climates (warm season grasses) and often as a single species rather than as part of a blend of various turf grasses.

I don't disagree with anything Becky mentioned. In fact, I agree there isn't really a good reason to ever bag your clippings and send them to the dump, but I've done it. I do everything possible to avoid it, including mowing my lawn several times at the same height to completely mulch them up to where they aren't noticeable, but sometimes it really is the only workable solution. That being said, the way I go about it is as follows: 1. Pull the grass catcher off the mower and stand it up so the opening is facing the sky. 2. Invert a large lawn bag over the top of the grass catcher and flip the whole thing over. This is hardly enough to fill the bag, but you really don't want to fill the whole bag - I usually fill mine about half to 2/3 full or else they get a little difficult to move around. After the initial dump into the lawn bag, I will lay the open end of the grass catcher on the opening of the lawn bag and pull the sides of the lawn bag up and around the grass catcher and then dump the grass catcher into the lawn bag. I don't think there is anything ground breaking here, but hopefully it's helpful.

What you should have done back then was to go over it again with the mower until it was all mixed down into the sod. For now the bugs will eat the decaying matter. As for new grass you are fortunate to live in an area where spring grass seeding is not a problem. You could rake with a hard rake to loosen the dead grass and the very top surface of soil. Scatter the seed and roll it down or walk on it all to press the new seed into the surface. Then if it s not raining/misting every day, water it lightly 3x per day just enough to keep the seed and surface moist. Don't saturate the soil and don't wash the seed away. The seed you get at a hardware store is likely to have rye, fescue, and possibly Kentucky bluegrass. These three grasses have three different germination times. Rye sprouts first in a week. Fescue sprouts in 2 weeks, and KBG takes 3 weeks to germinate. Keep watering daily as long as it takes to get about 80% germination. Then start backing off on the watering frequency and go up on the duration. Eventually you would be watering 1 inch every time you water. How often you water depends on the temperature. If your summer temp is in the 80s, then water 1 inch every 2 weeks. The soil surface will dry out completely before the grass roots need water. When you water deeply and infrequently like this, the roots will grow down deeper to get the moisture lower down.

You'll know if you have too many leaves: the compost will sit there and look at you and will not get warm. If you have too much grass, it will get very hot and will smell bad. Observe and adjust.