Snakes do need warmth to digest, but even the 'cooler' temps. are likely enough for your snake to digest, so just trust your snake to know what they need & want. When you get a chance (without disturbing your snake) double check the actual temperature IN the warm hide to make sure it's not too warm, but otherwise, don't worry- I've seen snakes do this before too.
Sometimes, it appears they deliberately want to slow down their digestion- I've noticed this after a snake has eaten a larger than usual meal- so that makes some sense to me-it's as if they don't want to overwhelm their digestive tract- or perhaps they get more nutrients from their food when it's not digested too fast. Anyway, your snake is surely not the first one to do this, nor are you the only one to wonder why.
And the mouse droppings aren't a big deal- "spot cleaning" to tidy up is fine. Leaving them may also stimulate your snake's appetite- the lingering scent may confuse them into nipping your "warm & wiggling" hand after they've digested this meal, for example. Oops!
On the other hand, if you're planning to get your snake on pre-killed rodents (fresh or f/t), saving these mouse turds to increase the scent of a defrosted mouse might be a good idea. (Just make sure you label what they are & don't store them where someone might think "candy"? haha)