Con - pilot, I'm sure you've figured it out already but a great way to safegueard against the unintended trip to a small secure room with a really bad view, is to put the "tip" inside something - passport paperwork etc. and offer it for the inspection of the tippee, it can all be brushed off as forgetfulness ( "OH that's where I left that $50 bill") if you end up "tipping" the wrong person, but will dissapear amazingly fast if the "tip" is required.