License Plate light error

It seems every other time I turn my lights on at light, I get an error light on the dash saying there is a problem with the license plate light bulb.. but every time i would check the lights were all on. I had the dealer take a look the other week when my car was in for warranty work and they just replaced the bulb and said fixed... i asked if they checked the connections and voltage to both bulbs but just got hte answer of its fixed..

Finally last night i found the the passenger side bulb was out.. and as soon as i tapped it it came right back on..

Anyone else having wiring issues? This is my first VW and just wondering if there is more to this problem than it seems..