Thanks OP. Even if it's been brought up before, it's a good reminder. Too late for those who didn't know when they winterized this year, but something to watch for when you hook up for the first time this spring.
When we purchased our two year old TT in Jan of '13 it was winterized. I took their word for it since I didn't plan on using it for a couple of months and didn't want to winterize it again after testing for leaks. That was a mistake. Thankfully I hooked up at home to test and flush before going out to camp. Toilet leaked. Guess where?
The local RV repair shop had a valve in stock (Yes, they are $35), and I replaced it myself. Now I put a weight on the pedal to open the valve while pumping the pink stuff. No problem since.