Thanks for that, my ego needed a boost!
A bad seal on the cap can and will cause this fault, it isn't that common, but does happen. The main reason I say that it isn't usually the gas cap is simply because that is what the message tells you, and what most generic 'car fix' sites will say(and very true on other models)
The cap on these can be visually checked for failure, there's a big rubber seal, and if it is cracking, then it won't seal up correctly.
More often then not though, these faults are the intermittent type, and will clear, and even fully pass the emissions monitors for a little while, and then come back later.