MyZone display tile in the gym

Hi everyone

When I'm at my gym, everyone working out with a MyZone on has their stats displayed on a screen. Every so often one of the tiles wiggles a bit. It's never more than one at a time and it's an animation rather than a glitch. I cannot figure out what I'm doing (or not doing) that causes it. If it's conveying information, that might be nice to know. My only theory is it tells the trainer something, but my trainer doesn't know.

Anyone else know?