This happened again today, from 3.5 l/100km to 99.9 l/100km
The computer scientist in me, is telling we are reaching some counter limit, the bike still functions properly and you just have to reset the counter (more an annoyance if that, than a breaking defect)
I said earlier that the first time was around 5000km, thinking back it wasn't, more like between 4000km and 5000km.
Today the bike was around 9775kms, the first service happen at around 1100km (not exactly) 9775-1100=8675, since this is the second time I had it if you divide that by 2 you have 4337, that is really close to 4294.967296 (to allow observation errors)
That 4294.967296 value is just taking a 32 bit unsigned integer (ranges from 0 to 4294967296) and considering the measure for distance traveled is in millimeters (this is just me speculating).
Bike will go to service tomorrow and I haven't bothered resetting it, should allow them to have a diagnostic when I mention it.