Cats have higher temps than we do...
(googling...) between 38 and 39 °C (101 and 102.2 °F) - wikipedia
And the itty bitty ones (as well as many adult cats) do sleep a lot.
I am not a cat expert at all, but it sounds normal that'd it feel hot to you... but if the adoption center had him as a little hot and you're worried, you should take it to a vet.
If all's well, at the least the vet could help provide you with some pointers on kitty care, and maybe double-check it's vaccinations and whatever else the little guys should have done when young. And maybe suggest how to check a kitty's temp... I have no idea on that.
Good luck with el gato! What's it's name, btw? Or post a too cute pic of it!