Put weed and feed down last night

You'll be fine. You want it to rain after you put it down. Didn't rain hard enough to carry it off unless you have bare spots.

I said it but craw could have said it as well. When you hit it with a jet of water it moves an inch and then you have to hit it with the jet again to move it another inch. In the lawn it won't go anywhere. Also, these are chemicals we are talking about, not just little pebbles. Once the granules start to break down the chemicals will bind to the soil.