Guys,

For a long while (6 months) I have had a warning light on saying "Oil level too high. Please visit workshop". It started showing 3 weeks after I acquired the car and was driving to Germany.

I have ignored it because it was definitely lying (checked oil level regularly - perfectly fine) It could be reset by popping the dip stick but would come back on after an hour or 6 of driving

The other day I had to get the battery replaced.

Imagine my surprise to find the warning light has cleared, and hasn't returned. Now I just have the service warning to deal with tomorrow (will be the last main dealer service this car gets but that's another story!)

Could it be that a "just starting to get sub-optimal" battery caused the oil too full warning?

A little unusual, but possible that slightly lower voltages could have been upsetting the oil level sensor.

Much more common for TPMS and SS warnings when the battery is starting to struggle.

Just monitor and see how it goes.

Find yourself a reliable independent service garage.