omega speedmaster question
my recently regulated speedmaster had been keeping excellent time up until 2-3 days ago. over a period of 15 days it only gained 10 secs, provided that i kept in crown up at night. imagine my surprise 2 days ago when i woke up to find that it suddenly gain 15sec overnight. since then it has continued to gain this amount of time when i leave it in this position. i also tried it crown up and got a similar gain. when things where going well crown up or crown down would result in a gain or loss of 1-2 sec overnight respectively. the watch was not dropped or magnetized as far as i know. what would account for this sudden change in timekeeping? i also want to point that the watch keeps excellent time when its on my wrist (about +1 sec/day)