This is scary! It seems like your printer is spying on you using tiny tracking dots which are automatically printed whenever you take a print out. Of course these dots are unique and can be tracked to your individual printer and are not visible to the naked eye (otherwise you won't have noticed them, innit?)
The US govt. has convinced most of the printer manufacturers to add this to every page. EFF highlighted the issue first and had issued a press release. Since then they have released a decoding guide that you can use to figure out how to find this. They also released a list of printers which either have or don't have the dots; and also point the fact that just a "No" does not mean there is no forensic watermarking present, it just means there could be some other kind of marking. Make sure you are consulting this list whenever you next buy your printer.