Not uncommon in the 24 hours. Audi had quick-fill systems, as I recall, in place on their cars to top them up when they were dominating in the 2000's. Nothing to do with it being a hybrid. Everything to do with beating the snot out of a motor for 24 hours. Guarantee that you run any engine at full throttle for as long as they do and you'll use some oil.
The fact they finished as well as they did, being relatively new to the race, is a massive accomplishment.