I see. For optimum digestion to make certain there is never a regurge problem, you might want to tap the temp up just a tad, maybe to 83 or so at the warm side of the spectrum, and this "could" even be the reason the snake is soaking after it eats, but we can't be certain of this unless there is a bit of experimentation done here. but those temps seem pretty good to me.
I will say that MANY of my snakes seek their water bowls when temps start getting a bit warm and reach about exactly 85 or above.
The fact that your snake does this may be because the water in the bowl is more of a constant temp than the ambient air when the room gets slightly cooler, so the water in the bowl would stay warmer for a bit longer than the air itself. So the snake might be attempting to raise it's temp one or two degrees higher. Not saying this for certain, but it certainly IS a possibility.
~Doug
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"a snake in the grass is a GOOD thing" 
my website -serpentinespecialties.webs.com