I reported a bug some time ago about shape keys and animations:
https://projects.blender.org/tracker/index.php?func=detail&aid=36737&group_id=9&atid=306
If you have an object ocluding a second object and a shape key animation on the first object makes the second object visible mouse over any sensor is still not seeing the second object.
The only way that I found to make the second object visible for the sensor is manually doing a reinstance of the physics mesh of the animated object.
I think that doing it automatically during the action has more sense than doing it manually.