Queen Conch acting strange

[Vagabond]

The last 3 days my Queen Conch has been acting out of the ordinary .

Usually she spends all her time on the sand gorging herself on any diatom algae. Now she spends all her time on the glass at the very top of the tank near the water surface, occasionally coming down only to bury herself in the sand.

Everyone else in the tank seems happy and all my water parameters are good.

Any ideas or is this maybe just a phase and normal behavior will resume in good time.

Scott