water damage to door speakers?

My son's Silverado has a pair of Infinity Kappas in the front doors. He tells me the speakers have been fried for a couple of weeks. He took the speakers out today, and he reports there was some rain water in some of the speaker recesses (It rained pretty much all day today). He directly wired the speakers to an amp, and neither one of them works (no intelligible music at all, just minimal crackling). He then hooked up different speakers to the existing wires in the doors and they worked, so that rules out wiring or amp channels as the problem.

These speakers are only 3-4 months old. I doubt he blew them by playing them this soon. I assisted/supervised the install, and I'm pretty sure there was no problem there. I've got to go back into work tonight so I don't have time tonight to look up Infinity's warranty info. Offhand does anybody think rain water running down inside the doors could ruin a speaker? If so, does a speaker manufacturer's warranty typically cover this as "Wear and Tear"? There's nothing wrong with the doors damage-wise, the speakers are the correct size for the install, and they were installed in the existing speaker cut-outs in the doors.

Thanks for any info you can shed, or any opinions you may have on this.

His Silverado is a 2003 model. I never thought about water getting onto the speakers in a door until yesterday. Come to think of it though, all car doors get water in them. I remember having to clean out the drain holes along the bottom edges of doors on a '65 Ford, a '74 Olds, and several  '71-74 imports when I was my son's age. (1974 was a magical year, BTW- that was the last year the gas tanks accomodated the nozzles for regular gas.) We had other cars that had the bottoms of the doors and tailgates rust out because we didn't realize they were rusting out from the inside. Being that I've never heard of this happening before, I guess most people either sell their vehicles with the speakers in them (or get them stolen) before the speakers crap out. Or maybe the fact that he washes his truck 50 times a week has something to do with it. hmmm....

Are those XTC baffles the enclosures that are supposed to improve the sound quality and/or volume of the speakers? I was thinking of wrapping the speakers in some kind of Baggie, but my son mentioned something about foam enclosures last night. Maybe he could get some of those foam insulators that are supposed to keep the hose bibs on the outside of the house from freezing. All the important answers to life can be found at Home Depot, you know.  ;>)