Bedford's housing stock runs from 1953 up through 2014, with the median build year sitting around 1992, and most of the 31 named areas in this service territory are dominated by 1980s and 90s construction. That matters here specifically: a track system installed in 1988 has had over three decades of seasonal expansion and contraction to work bolts loose, and nobody's been out to re-torque them since the house was built.
Add a moderate heat climate band to that math. Steel track brackets expand slightly in summer heat and contract back in cooler months, and that cycle - repeated every year for thirty-plus years on an original installation - is exactly what loosens the lag screws holding a track to the jamb. It's not dramatic failure, it's slow drift, until one day the door rides just far enough off true that a roller pops the rail. Newer builds in the service area, especially anything from the 2000s on, tend to have better bracket hardware and haven't had the decades of cycling yet, so this complaint skews toward the older end of that 1953-2014 range.