Gas smell from rear
 

Hey I was curious if anyone could help me figure this out. I have had a few chinese scooters. Got a 150 in the mail assembled it. Got a new belt swapped out some chinacrap bolts etc etc. New oil gear oil/engine oil its running great. I swapped out the fuel lines for tygon and got some new vac lines. Its hard to say if this started with the new fuel lines since this is such a new scooter. I keep it in my garage and there is a moderate gas smell coming from the rear of the scooter. I don't believe mine has a gas tank vent because when I had all my panels off I didn't see anything like that. It only has a cap and the mount for the gas gauge. I see my gas cap is vented. Could this gas be venting and sinking down through the rear and thats where I smell it. I check all my lines and they seem nice and tight. Used tissue to check and no wet spots. No drop in gas level. I even got a new fuel filter thinking it was a vent in the crap plastic. It smells around the underside of the tank. I tried to sniff and see if it was the petcock and I just can't tell damnit. Anyone have an experience like this? how much should worry about the moderate gas smell in the garage. Frustrated.