door-hacking?

We have all heard of drive-by's on the 802.11 side
of things.......blah, blah.....

Has anyone heard of tools/means to decipher garage-door
openers? sniffers or scanners?

My girlfriend had her door go up in the middle of the night
on Sunday....twice. I changed the code an all was well.
Only thing unusual I noticed was a neighbor working in hos
garage at the time (midnight) and two shelves of computer monitors
in there....I guess I got to thinking about the possibility...?