It's an interesting assumption and I know I'd like to know more. I mean, it's not outside the realm of the possible.
For myself, I'm aware that NASA was very careful about sending stuff up (to mars) and bringing stuff back (astronauts), and had cleaning and quarrantining procedures.
As a guy who creates solutions and processes, it's pretty easy for me to imagine how that MIGHT accomplished be, but I couldn't point to any article or show I saw recently that confirms it.
Here's what we know:
NASA is paranoid/careful about germs
NASA only sends up healthy astronauts
NASA does sterilize some projects like the Mars Rover to the nth degree
NASA does carefully manage what goes up in a payload as weight tolerances are calculated
So, a strip-down, shower, change into certified clean space gear, and full check of all incoming equipment before it gets put onto the launch vessel seems probable.
But as we also know, astronauts bring up personal items, including personal computing devices (I once read that the 386 laptops the astronauts carried on one mission were more powerful than the onboard computers in the space shuttle as those computers were designed, built, certified in the 1970s).
So there's likely some wiggle room for some small utility objects like a USB drive to get past the basic screening, and forgotten as a security risk.
