I have some problems on my 300E that act like "wounds"...they mysteriously heal themselves over a period of time, instead of suddenly disappearing.

But occasionally, the wound may "re-open"...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car