It would be just thoughts...but I seem to be having some of the same things happening with my wood. I used 2 pieces of oak,hickory,and cherry on two PBs that I smoked last night. Normally the cherry is just a tad bit drier than the other two and burns to ashes very quickly. This time my wood was charred real good but not used up as usual, EVEN the cherry.
I just seem to think that it has to be something to do with the 3 weeks of 90% humidity that we have had here in our part of the country or maybe it could be it is drawing some moisture back in the wood.
I, like you have a good smoke flavor to the product, so oh well! It's just not worth the effort to dry it out more,IMO.