Know what is slightly amusing about this - is because 2 weeks ago the same thing happened to me, except in a 2 seat Grumman T-Cat. The lock was old, and you wouldn't tell if the damn thing was open or closed b/c it was done by key. So while in the flight, the vibration ended up moving the tumbler back into position - and upon landing, we got a nice surprise. Well, not really a nice surprise. We could barely slide the canopy open enough to tell the line guy somehow we'd been forest gumped into locking ourselves inside with no way of escape. SO after about 45 minutes of the guy trying to get the lock to engage, it slid back.
Life is good.
Wolf