Do you think this is morally wrong?

I found a ten pound note in a corridor lying on the floor and i was the only person around so i picked it up. i didnt take it to reception because i always do that and the rule is if it isnt claimed withing 14 days you get it but they always take it for themselves! so i took it. I dont have any money right now and it must have come from a rich person (because it was in a rich person place). So is this wrong?