Yes, me and corncob pipes go way back. This does seem to be a common problem with MM's; not the first time I've heard of this. I blame it on genetic manipulation, myself. I never had this problem in the 70's and now with all the GM corn (and the resulting COBS) we've seen this. The guys I know buy several pipes and wait several days between smoking, let them have a lot of rest, they are very moisture sensitive, much more so than briar.
Just curious, did it get a good coat of shellac on the bottom of the cob? I've seen some that were lacking on a good coat, might pay to supplement it. Gen'l McArthur apparently never had these problems, or if he did, history doesn't record it! He liked the "tall" ones.