I also had this issue, with a ***Wahl 7063-017*** (face foil shaver) - bought from Amazon, 6 months old, well cared for, daily use.
I don't think it's a common problem as this is one of the few references on the web!
After 24 hours of not being used, for some strange reason my shaver just turned itself on, and ran for more than 1 hour till the battery was flat.
Had to return to Amazon for a refund.
Shame, as it was quite good, at an affordable price, and otherwise seemed well-built (with a long battery life).