There are several possible causes for petrol in the oil,
Simple and most likely option being a lot of short runs or letting sit and idle without getting a good hot run allows the enriched mixture to wash down the bores into the oil, depending on how bad the contamination is this may not be too tragic as a tiny amount of fuel can cause a real smell in warm oil. Just remember if you give the car a good run the petrol and inevitable moisture in the oil will evaporate and the oil level will drop and need to be monitored. If there is doubt change the oil but if you have no fault codes and the car is running well my guess is it's not a real problem.
If the contamination is bad I'd suspect a leaking injector dripping fuel in the cylinder even after stopping, at start-up you may get some rough running or exhaust petrol smell.
With the complex fuel return system a blocked crankcase breather could lead to fuel ending up in the wrong place, blocked breathers are quite common.
Sticky piston rings are possible on an underused engine and may shift with a good run.
Worn rings or a scored cylinder bore are the worst case scenario and may be accompanied by lots of blow-past pressure in the crankcase and heavy oil consumption, I'd definitely eliminate the other possibles first although a pressure test and borescope examination don't require stripping down the engine.
If the oil is badly contaminated it needs changing ASAP. If not and the cars been stood or underused a good hot run may clear the problem, then monitor regularly.
