I was playing around reading and clearing codes with INPA and after I started my car I noticed the Oil Service light come on. It said "-37000mls". Which funnily enough it the mileage of the car.
My next oil service is booked in before Christmas so I just reset the warning and it went back to being 20000mls until next due.
Since then the counter has gone back to 0 again several times (not seen it return to -37000 again).

It seems to do it after I plug into the OBDII port but not every time, just on the odd occasion. It's done it a couple of times while flashing with my OFT.

Has anyone experienced anything like this before? Could it be a fault with my oil condition sensor?