Here's a strange one for you.

Last night I prepared the container with the guppies for my non-eatingT.s.parietalis - Red Sided Garter Snake. When it came time to get the 3 non-eaters I looked in the tub and saw that I had left
a yogurt lid in there. I picked it up and found only the 3 non-eaters under it.
Why would these 3 choose a spot away from the main group and the warmth of the under tank heater?
Any thoughts on this would be great.