Not strange at all.
The driftwood, if large enough, could possibly be leaching tannins that lowers your pH. Parameter shifts can easily cause crypt melt. They'll grow back quickly, though. Just remove the dead leaves and allow the rhizome to sprout new leaves.
Unfortunately, you can't just remove the driftwood to find out if it's the problem. You also can't just do a water change. Primarily because crypts are so easily impacted by parameter shifts. If the plant has already been impacted, water changes or removal of the wood won't stop it from doing its thing.
Last edited by somewhatshocked; 02-01-2013 at 01:33 PM.