Where the Mirage Drive is supported by the kayak, the area that takes the most punishment, you can get wear and eventually some leakage on older versions of the Mirage Drive kayaks which were not built sturdy enough.
Hobie recently sent owners a kit for reinforcing these Drive fitting areas, but the good news is that they are very responsive to issues with their kayaks. Excellent customer service in my experience, so go and talk to your dealer.
Here's a forum on their website:
http://www.hobiecat.com/community/viewforum.php?f=11