No, wasn't a joke. I went downstairs now and checked the pressure. It was around 15 PSI ... yikes! I also found a nail in the rear tire! Looks like I will be visiting the dealer tomorrow.
Any idea how much time this takes at the dealer? Is there any tire warranty (as standard) etc.? I guess not?
Interestingly, looks like the TPMS did not come on when I parked my car because the tire hadn't lost too much air. But overnight, it looks like it leaked quite a bit ...