I have had the same thing happen to two of my oldest controllers.
What's interesting to note (at least, for me) is that I have another controller that is a Dualshock controller and I haven't had it lock-up on me at all. I've also had this controller for as long as the Dualshock controllers have been out.
Are your controllers Dualshock? In other words, does it have the ability to rumble? If so, that throws my theory of the older controllers causing something to hiccup. If not, well, I suggest getting a Dualshock controller since I haven't had any lock-up issues with it yet.
Oh, and for the record, my older controllers still lock-up on me. I just don't use them for gaming -- mostly watching movies while my gaming controller recharges.