Yesterday, I was flying on an old 767-200 and during takeoff, one of the locking mechanisms on the overhead luggage compartments for the seats in front of me released, exposing the carry-on luggage. I didn't know what to do - for a couple minute you could see the luggage shifting over the edge, and it made me very nervous. Luckily, a minute later we reached cruising altitude and the flight attendant came to close it.

What is the appropriate thing to do?

Stand up and close it? (seat belt sign was on)
Notify person in front?
Get ready to catch any falling 'debris'?