Have you tried shouting him? I'm sure he'll be fine but I would have a quick look round for him if you can just in case, fingers crossed he'll turn up safe
Mine used to have me up all hours looking for them
I remember a few years ago, 3 of my own and 2 ferals were all out and no sign of any of them, I shouted and shouted and nothing. I had visions of one of them being trapped somewhere and all the others looking on helplessly
When I was getting to the crying stage, Tiger suddenly appeared from the woods followed by Sally, Alfie, Sooty and Mika, I could have throttled the lot of them, they must have been playing with a mouse or something in the woods and thought that was better than coming home