My roll-up garage door sticks occasionally, only in very cold (below 0 degrees F for several days) weather. It's not freezing to the garage slab; it lifts about 6", sticks, and the garage door closer shuts down.

I had this problem several winters ago and thought I'd cured it by lubricating the rollers with penetrating oil and never-seize on the tracks; the problem recently started up again.

Any suggestions?

P.S. The door is about 10 years old, so it's out of warranty. The installer isn't interested in servicing the door, so that's not an option. I've searched thoroughly to find a protruding fastener, or anything, that a roller might hang up on... I've found nothing obvious.