We have a squeaky door latch as well. My wife says the simple solution is to close the door, lock the deadbolt, and then open the door latch. It has worked for us.
Chad & Peg with Remedy (Peg's Medical Alert Puppy)
2006 Winnebago Tour 40FD DP / Allison / Freightliner
Towing 2009 Chevy Cobalt SS Turbo (Dolly)