Did a trip to Germany the end of September, and no problems going out, not even a question. But coming back Matt was in front of me and when his bag went through the xray machine, there was his marker in full glory, stood up in his bag. The guy nearly fell off his chair, he had to look twice, maybe three times, before he could believe his eyes. Needless to say he had his bag opened and the Angel brought out in the middle of the airport, and after a few explanations we were on our way, no probs.
So don't worry just be prepared for an explanation or two. Oh yes make sure there is no gas in your bottle and it is seperate from the reg.