I had the same issue few days ago. I toke my car out after a week of it being parked, i got the tire pressure warning on the idrive just after 1km of driving & as usual i panicked. I still drove the car as i didn't see any visible loss of air in any of the tyres. Got them checked at the near gas station that was 5kms away & the rear left was only 10psi, i fill 32psi all around as i drive alone & the roads are terrible this side of the world. After that i drove back home & got the tyre checked today by a tyre specialist & there is no sign of a puncture. The tyre guy says could be the valve or some dirt got into it anyways its fine now but he recommended me to change my tyres as they done around 20k kms. Is that the tyre life for stock rfts?