With a median build year around 1984, a lot of these doors and their track hardware are old enough that the original anchors have started to work loose from the framing, especially where the garage faces west or south and takes the brunt of afternoon sun and humidity swings. The climate here runs mild temperate - no hard freeze-thaw cycle doing damage - but year-round humidity still corrodes fasteners slowly, and a loosened anchor lets the track flex every time the door runs, until one day it flexes too far and a roller jumps clear. The other common cause is simpler: something hit the door, a car bumper, a bike, a stray ladder, and bent the bottom section of track enough that the rollers can't track straight anymore. Either way, the repair starts with the track, not the door panel, because a straight panel riding bent rail will come off again.