Interesting.....I actually had to replace a faulty factory Varta battery (that's a tongue twister) about 10 days ago, I upgraded to an AGM stop start and coded the change in VCDS with no issues. The new battery has been in and working with no issues for the last ten days, I've also been checking the battery Measuring blocks in VCDS on a daily basis and all the stats have been excellent. I agree there's no smoke without fire but very strange that the bulb light should take ten days to come up on a newer\better\healthier battery than what was in place before. Makes me think it's not related but a good shout....?