Yea, you should of pulled the battery instantly and let it completely dry out. 24 hours (or over night) is best for the safe side.
Or you can use a blow dryer on the cool setting to dry it out. There's probably water or something underneath the keypad screwing around the connections. Water damage has been known to cause the glitches in keyboard. Since it's water damage insurance won't cover it, so if it keeps happening you may just be SOL. Sorry.
If you really get desperate you might want to take it apart and try cleaning. Just for a last last last resort. (NOT RECOMMENDED) but if it's your only hope. here is a guide. I take no responsibility in your actions either.
The Picture Guide
Video How to
Hope this helps