Hey did you know that most Hotels have "business centers" for the guests to pop in and print out airline boarding passes and such, and that often these are located just off the lobby, and unless you look like a hobo, no one will question you using them? Likewise, did you know that most hotels offer free wireless internet without login in the lobby as well?
Seriously though, I can't see how they would track the code to a specific printer without a search. I suppose they could eventually get a public IP off a networked machine, which could give them a hint, but a printer used in isolation would have to be found physically. Of course now the code is known, I would expect "clean" roms to show up you can load that will eradicate the dots.
Sort of reminds me of Orson Scott Cards's Ender books. The characters started embedding a code in images, just changing a pixel here and there and then posting it. Seriously, just because the government can monitor/record you, doesn't mean they have the means or manpower to finding and decrypting conversations. The internet is the largest and best weapon and defense against the government we have-- which is why they are so keen on trying to find ways of shutting it down.