It is not uncommon to have a little raspy cough for a few days after having surgery because of being tubed. Just watch it, and it it looks to be getting more serious, advise your vet.

my Ruby had cherry eye surgery, she had a rattle, and she would hack like she needed to cough something up. It cleared up after about a week. I am pretty sure it was from the tube, irritating "stuff" (the vet seems to agree). I'd give it a couple of days. Hope this helps ya.