Stevdart - I considered that (screw torque), but ruled it out based on a couple of things... I just switched out the two suspect drivers with ones from the LCC and none of the screws were over torqued. Additionally, I noticed the adhesive starting to break loose on one surround from the LCC speakers.
Add to that the cracking resembles aging rubber (spider), and has lost a significant amount of flexibility.
This is after 5 years of service, with all bass going through the sub. My 20 year old ADS's that survived college abuse don't show any sign of age.... hmmmm