I've noticed this twice in my truck a few months ago, haven't been paying attention since, but I don't think it's just a standard "start up procedure". Like the gas gauge for example, it will swing to empty and then back down to where it should be. It does it every time like clockwork, it's predictable. The OD sits at 9001 (or whatever) and then within a few seconds goes to 9010. It doesn't do it every time, in fact it I've only noticed it absentmindedly twice and other times I've looked for that behaviour but not seen it happen.
So why would it do that? Would it make sense for the truck to be at 9010 upon shutoff, drop to 9001 and then cycle back up to 9010 within 1 or 2 seconds? Makes no sense to me. Looks like some sort of glitch. I will try and capture it on my phone too if I can remember in time.\
Makes me wonder if that's the reason why I'm getting such good gas mileage. I sit at about 11 L/100km (21 mpg) in my daily rural/highway driving, but often drop down to 9.7 or 9.8 (24 mpg) on longer highway trips. Truck might be thinking I'm driving more KM on one tank than I actually am.