I completely agree with
tsac, even the smallest amount of moisture can affect your bb. Check the moisture indicators on the battery and the bb chassis.
If they show any amount of red - it will not be covered by warranty. It may be covered by insurance (if you have one).
Read this thread
Got Your BlackBerry Wet? - BlackBerryFAQ
I had a similar issue with 9700 after my wife used the phone in the rain. After drying the phone thoroughly I ended up with a similar issue. It was an easy fix, I bought a keyboard membrane on ebay (dirt cheap), dis-assembly instructions are available on youtube, and 15 min later I had a perfectly working phone!!!