I don't want to be a hypochondriac but while researching the Calici Virus (FCV) I learned that a sign of it can be drooling. I'm not saying your cat has Calici, I just wanted to bring it up.
Our recently adopted (4 weeks ago) stray (Babbiness) had also always been a bit "irritable" when getting pet around her hind quarters and I originally thought she was just moody but I also read that "swollen joints" can be another symptom. The soreness seemed more like moodiness because she seemed to be perfectly fine otherwise and showed no signs of discomfort. We didn't realize she had a sickness until her front paws got really sore & raw (causing her to limp severely) at the same time her nose got raw and formed a small ulcer looking spot that was bloody as well. As soon as those symptoms showed up we took her to the vet and that's when we found out she had Calici.
The good news is that after 3 days of treatment her nose is looking better, she's walking better, she no longer is irritated by petting those same areas and I think she's drooling less (only an "improvement" if it was associated with the virus). Calici is very contagious and is probably what caused my other cat (Tigger) to get a cold that almost turned into pneumonia a wk ago too. Babbiness is currently being separated from my other 3 cats until she gets a bit better (probably another day or two).
Again, I'm not saying that drooling automatically is a bad sign. I just wanted to get this out since I'm going through it right now...http://www.cfa.org/articles/health/calici.htmlhttp://www.225batonrouge.com/blogs/u...leashed102808/