Loose bolt in front passenger footwell after window tint

Just picked my sealion 7 up from getting the front windows tinted, and noticed a loose 8.8 flange bolt lying in the front passenger footwell. It looks totally clean, almost like it hasn't been used. I've looked all through the front of the car, along the dash, under and around the seat, checked the door trim to see if it's been fitted correctly, and found absolutely nothing out of the ordinary. The door also has no noticeable rattle while driving or opening/closing the door. Any ideas?