ucdavis4PT0gpa
I should Work at Oakley
Depends. If you take care of them the flex coupler shouldn't loosen that much but if you're pretty rough with them they can loosen. It's fixable though. Just have to send them in to Oakley for a tune up but it does cost $70+/-.
I've had mine for 7 years and while the flex coupler moves it's not nearly as bad as some that I've seen where the frame can pretty much be pretzeled.
Showing care with the piece, especially if worn in a rotation, can lead to coupler life in excess of 10 years...but you never can tell buying used. I have yet to purchase a used pair where the loose-ness was a) described correctly and b) little enough to warrant NOT sending them in.