I will clean up the battery cables and double check the connection at the starter. It is a remanufactured unit, and I had the AutoZone guy test it before I bought it. If the problem continues I'll take it back and have it checked again.

It doesn't happen every time I try to start. It'* happened a total of 3 times all in the past week and a half. The first two times were after driving in heavy rain. But yesterday it was completely dry out...

As always, thanks for the help.