Mine does, too. It started after a few years in.
It’s a bit of a nuisance having to fold it back in every time, but I just live with it. The little nub that catches the extension might have worn down, not sure. I haven’t taken the needle nose pliers to any part of the bracelet yet - maybe something could be tweaked to tighten it up. Or you could mention it to your AD or watchmaker and let them do it, which is probably the safer option.
My trusty 2010 orange bezel (now nicely faded) PO 2500 resides on a black Uncle Seiko GL831 strap most of the time, anyway. It’s like a whole different watch - looks great, perfectly balanced, and comfortable for days on end.