I think that this may be Orchard Grass left over from the original (builder) seed. I use a Lesco Fescue Seed and doubt that these weeds are from it. It is very unappealing and I don't see what I can do other than round it up and re-seed (in the fall of course). I hand pick at it but there is just way too much to think I can pick it all out. Last pic is in a different area of the same lawn. This is 5 days of growth. As you can see, it grows fast and doesn't cut well. I use a Exmark Hp 23/46.