A couple of questions,
Is there a lot of petrol?
How much petrol was in the tank?
It is possible that with it sitting that long, a small amount of petrol would leak though the carbs into the cylinder and leak passed the piston rings.
If it's not too much petrol, more smell than you can see, I wouldn't worry about it.
Change the oil, but keep an eye on the level, or smell.
Hope this is what your asking and this helps.
BTW, I hope you are useing fresh petrol in the tank...
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