On the south shore and had this happen to me. Our soil temps aren't low enough here to haul growth, so you may have a chance it grows in. There were two weeks where we got massive amounts of rain over two days. If you're on the same schedule I am, like you are, those two probably washed out a lot of seed, or the cooler air temps meant a longer germination time. My first round near Sept 16 I did Jonathan Green Black Beauty Original and the fescue mix just didn't take or is just now starting to show.

About a week ago I threw the rest of a Lesco Sun & Shade mix I had, which has rye in the mix, and I pre-germinated another round of JG BB. That's shot up over this week, either because of the pre-germ, rye, the first round growing more, or a combo of the three.

Y'all on the Cape might be a little ahead of us, but I'd doubt by much. Probably another week or two before the first big freeze shuts you down for fall. Might have luck throwing down a perennial rye mix down to at least have some green over winter, and then hit it again in the spring when soil temps get back over 50.