While watching certain movies with action, I notice my SuperSat 50C often rotates a few inches due to bass vibration. Is this a known issue?

My Setup:
- The bass dial on my Triton 2's are set to 11 o'clock.
- The SuperSat 50C is resting on a flat glass surface, resting on the stand brackets that came out of the box.
- Typically watch movies around -15.0 to -8.0 dB with no volume control settings.

Well, either the Tritons are rocking the cabinet and causing it to move (nothing to do about that really other than turn it down or move them further away), or too much bass is getting to the 50C (center channel crossover should be set at 120Hz). If everything is set right and it continues I would suggest putting small pads on the bottom front corners of the 50C or the surface it rests on - the surface may be to smooth and slick for the also-smooth 50C cabinet.