I have not seen one "crack" per se, but I have seen three that have failed. The first one the take down lever hole in the fram streched out to an oval shape. The other two the mag releases failed to retain the magazines. In all three instances the factory returned the weapons untouched, stating that since the weapons had been refinished the frames were no longer within tolerance and thus, the failures.
Needless to say all three guns were retired. The owner of the first one no only carrys LB 1911s and the other only carrys Glock.
Just to clarify, this is not second hand info, I was on the range when all three failures happened.