Strange telescoping behavior

[Bogertophis]

Maybe? Since the heat pits would pick up the heat signature? Then again you don't typically see them reaching up towards bulbs shining into their enclosures...

I'd tend to favor the heat explanation, but I'm not sure how little heat they can detect though? Maybe it's also instinctive to seek out the light (sun) for warmth, even if they aren't quite feeling it. Perhaps he's trying to tell you he's ready for a day of basking on the beach in the Bahamas?

Maybe they do the same thing in their enclosures but only at first (& you didn't notice?), & then they get used to that light so it doesn't entice their curiosity.

Either that or he's been doing some deep reading about the afterlife & being drawn into the light...