I planted a few behind the house back in April. I was just messing around, not doing a dove plot. They've been dead, dried up, and gone for at least a month now. They did produce seed very well though.
I certainly don't know much, but I understand annuals to put all their effort into producing seed. They've got one shot. They aren't like clover where they'll "die" off and put their resources into the root system and then come back once conditions are favorable. I'm curious what happened in your case.
