So far so good....
Down here along the coast (CT), no problems so far. I think you are local, so I would assume it was all watered in, because of the rain we had all season. We put ours down a little bit later - 3rd application, after 2 pre-emergents, so it was going down while the grass was really growing well. Did you put it down too early, or during that short hot/dry spell we had early in the season?
I have had lawns treated with merit sandwiched between bad lawns with nasty infestations. For the last few years its been like there is an invisible fence.