Are you going to Charge for your digital files?
That's money out of your pocket from prints. I always explain to my clients the difference between myself printing it for them and them taking it to Walgreens/Eckerds/CVS/Walmart etc.
Also ... that's your work just going to whomever.
Or at least stamp your bug on there and request that they not crop it out.
You can't stop anyone from printing your work ... but if your bug is on there then they would have to crop then print (which most people won't do out of respect for the photographer) or if they print it with your bug ... it's free advertising.
This is a defining moment that separates you from the Amateur level to the Pro level ... and it keeps the Still Photography field even and true and also educates people on the hard work and reasoning behind paying for still custom pro work.