As a preventative check, take a look at your lower door track. Many of them are designed with weep holes on the inside that are designed to allow water that gets into the track a way out. IF the door is incorrectly caulked, they can be easily plugged up, allowing water to leak outside of the track...right where you are having the problem.
No sense fixing damage only to have it reappear because the cause was not addressed.
[URL]http://www.meyerrenovations.com[/URL] Beware of the "do-it-all contractor".