If they painted both doors and the fender, chances are they did the bumper too, probably someone clipped it or previous owner backed it down the side of something. Typically if they repair instead of replace the bumper, they heat gun out the dents, fill and then paint. The filler doesn't flex as well as the bumper, so if the bumper flexes, especially when it is cold, the filler will just pop out and look like that. It cost more, but the proper repair is to replace the bumper and repaint.
I would talk to the car wash and see what they say - might pay for part of the repair at least, never hurts to ask.
2008 E93 335i, MHD, HPF IC, Injen Intake, AR DPs, Alpina TCU Flash
2016 X5 M-sport 35i JB Stage 1
2013 Mercedes C63 AMG, ROW airboxes, power pipe, Eurocharged V6 Flame tune 540 HP