Yes- men can leak semen at other times rather than just during sexual arousal and during sexual intercourse. This can happen during nocturnal emissions- meaning a man can ejaculate during his sleep, either aware or or not away that this is happening. This is a very normal occurance. You can read more about it at
http://en.wikipedia.org/wiki/Nocturnal_emission
If the answer is acceptable please click the accept button so the question can be closed.