that happened to a laver i had in 2006, when i went to the astro nets which hadnt quite dried out. It looks a bit like a blister/swelling???
i let it dry out (with the help of a hairdryer) and it went down but always looked a bit different to the rest of the face. Mid way throught he season i cracked one off the toe and it cracked in the exact place, front through to the back.
I would let it dry out and the wrap the toe all the way round the back a few times with fibreglass tape.
The bat was great and was a Jayasuriya cast off (too heavy.)