I don’t remember seeing that before - must be humidity plus MDF trim. Neither wood nor MDF expands significantly from heat. Moisture, on the other hand, makes wood expand across the grain, not along it - so boards get thicker and wider, but not longer. MDF, however, swells in all directions when exposed to moisture. I’m surprised that this is the only piece affected though. Perhaps who installed it forgot to nail in the middle.

This is exactly the kind of work I do for living. Not garage door trim but “where do I even call and ask” type of work. Unfortunelately I don’t live in the US.

I can give you one tip however: aluminium can be cut with woodworking tools so if you have a mitre saw and a drill you could probably buy, cut and install the trim yourself.