Snakes often sit in their bowls,....sometimes it is because conditions(temps) are not optimum, and are too warm, other times it can be from acquiring mite infestations, too low a humidity, etc..., it really can depend on many things at any given time and circumstance.
If your temps are in the high 80's or so on ONE SIDE ONLY! of it's enclosure, and the other side is in the mid 70's(pretty optimum for self-thermoregulation), I simply suspect it is just trying to re-hydrate itself after being gone for so long in the much drier winter environment.
Yes, definitely on the thin side for sure, but I can certainly understand why depending on how long it has been gone. Good luck getting it back up to snuff! 
~Doug
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"a snake in the grass is a GOOD thing" 
my website -serpentinespecialties.webs.com