[BeaglesToo]

When I was out shooting some photos today every thing on the camera was working fine for about an hour and a half then I went to take an other shot when my focus went all yacky.I honestly don't think I hit any of the buttons by accident.So I shut it off, and then tried again.Same thing happened.So I shut it off.I tried it about 2 hours after I got home and the focus was back to nomal.Has any-one else ever had this happen?
canon EF-S18-55mm f3.5-5.6ll lens
Lorraine