A year is a long enough time to get acclamated to the new place, really it only takes a month, and 2 weeks to realign their location-sense.
Male cats always like to be on top though, even if they are the little guys. Usually when theres competition between a male and any other cat, the male (or both, if theres two) will spray to try to exert dominance. Could be your little kitty is growing up and wants to rule his kingdom?
Prozac, thats just great though, he'll be more happy about taking them after a week of being on them...
