1995 VW Cabrio sometimes stalls after fueling
 

I have a 1995 Cabrio that in the last year or two will stall after fueling. I've let it sit and sfter a few hours it will start. I had it towed to my mechanic last year and the next moring it started just fine the mechanic could find nothing wrong with it. I think it may have to do with the fuel cap / vent. Any ideas or similar experiences?