Mileage counter reading wrong after unplugging battery?

[Dme3]

Don't know if i'm going crazy or something, but something is off in the mileage i did with the previous tank.

I filled it up on february 1st full like i always do, did around 60-70 miles until i unplugged the battery to do the valve cover change + gasket, really took my time so plugged it back after 2 days and i'm pretty sure the trip computer and everything except total mileage was reset. I remember average consumption being really high after the rest drive and then slowly settling to what my all time MPG is in a couple of days driving to work.

So yesterday i had 210 miles on my trip computer and today when i filled the tank up, the difference in mileage is 225 miles from the last full tank.

It's like that 60-70 miles i did before i unplugged the battery are missing, i went through my calendar and i 100% did around 280 miles this month so far (which is in line with what i usually do per tank), 15 commutes to work and back is 225 miles alone and i haven't only driven to work and back.

Really confused and it seems the mileage after plugging the battery back is accurate, as is what i did on today's new tank of fuel.

I guess when i hit 119.940 miles on the speedo, it will be 120.000 in reality or what

[taslaughtery]

The trip computer stuff (avg speed, avg MPG, trip odo) are all stored in short-term memory in the Kombi (gauge cluster computer) and are reset to 0 if there is no power from the battery. Actual mileage is stored in multiple places and is not lost when power is disconnected.