Just for info, I just got my battery changed, after 2 years! My MB White CD's battery was a little deformed (bulging), and I immediately called AppleCare, after talking for less than 10 minutes (with someone with a heavy slang, later found out the call was directed to Apple Europe), they agreed to replace mine and gave me a case number. Got my new battery few days later.

For info, my AppleCare expired last month! Apple ROCKS!

Dont know it's safe or not, but you can try to spray some WD-40 in it, push it in out again. If ok let it dry before using again.