I'm tired is a poor excuse, he could have made something up. He could be genuine there is only one way to find out, ask him. Good luck and let us know what happens.
If you like him, invite him out to somewhere that you're going to anyway so you're not wasting time on him if he's a no show.
If he does not reply/declines/bails out then you know to move on.
Make him make the effort to come to you he was the one that blew you off