I had the water damage sticker activate on my RAZR after owning it for a year or so. Honestly don't know when it happened, but I know I never got it wet. I have seen people selling new stickers pop up over eBay for those, but the design and complexity of the location has changed since the RAZR days.
Plus I could never drop it in water, replace the sticker, and go in claiming something was wrong. If I did it, my fault, my dime. Just saying I've seen them floating around the web.