Has anyone had this problem before?

My male cat, Frank, didn't come in last night until after we went to bed. In the morning I noticed his usual meowing was scratchy and hoarse and I could barely hear it, its still like that now. He seems well otherwise, still eating etc.

God knows what he got up to last nght! he is meant to come in for curfew at 6 but obviously wanted to stay out partying instead.

Just wondered if anyone knows the cause?

thanks!