Yep...that oil also is used to lubricate the crank..if you remember, take a glance at your plugs, double check, but it running fine, and no problems, then i say its work'n.
Using the oil pump/injection system, at idle, the motor is at a mix of 100/1, then in use, more throttle, the more oil, as you say, you've seen it drop for you to add, its work'n...