(Rare) Dynafit Failure.

Upon disassembling my Vertical ST bindings for the first time i noticed a small crack in the side of the compensation plate. After taking the binding apart, the compensation plate was indeed in two pieces.
The bindings are from april 2009, has seen probably between 40 and 50 days of use. The use they have seen have been everything from regular back-country touring to icy in bound skiing to expedition use involving multiple plane and mule rides.
In other words, they've been banged around quite a bit.
I didn't notice anything unusual skiing the binding a couple of days ago, so I don't really know how long it's been broken.
I will of course be replacing the broken part, even though the binding seems to be skiable.
Have anybody else seen or heard of this mode of failure.
I should state that I haven't disassembled the binding before, hence I don't think over tightening the top plate screws (at least not by me) could be the reason for the failure.
Enjoy the spring.