XC70: Engine “Engine oil level. Service required”

[Ian21401]

XC 70. 2011my. 127936 miles. Daughter’s car.
Above message displayed when checking oil level display during weekly check. Display shows oil level is too high.
Is checked weekly. Has always been OK until today.
Dealer serviced 28/01/19 @ 114553 miles so next service due in January.
Daughter monitors her average fuel consumption by the dash display. She commented just yesterday that her average had dropped dramatically last week to 25mpg. She refuelled a couple of days ago and average is now showing as 35mpg.
Could this excess fuel consumption be something caused by a “regeneration” which has gone wrong and caused fuel to go into the sump, and caused the increase in oil level?
I’m a little concerned as she needs the car for her work. (Travels from client to client as a pet carer.) The very nature of her job means that the car is regularly doing short journeys which we know is not conducive to regeneration but the car has been used like this for nearly 3 years with the occasional longer run and this is the first time there has been a problem.
We have obtained a “proper” dipstick kit but I haven’t yet managed to fit it as I was intending to do so after the car’s next dealer service in January.
Comments and opinions will be appreciated.