The Huffington Post article (huffingtonpost.com) about iOS apps that upload contacts in the clear & store them on their servers is pretty concerning. Where I grew up, this would have been considered totally inappropriate & scandalous. I'd be outraged if I'd had this done to me. As it is, I'm glad that most of the people I help with their stuff aren't big into the social networking stuff, so should be OK.
Not OK, & never would have dreamed that anybody else would have thought it would be!
Do we know why the reference article (& its embedded references) cite iOS, & all call out iPhone specifically, but don't mention iPad? That certainly has a whole set of contacts information.
My first thought would be to check for a stuck key on your keyboard. But if it's happened on multiple computers that's out. Do you use any/some/lots of Firefox extensions? Are any or all of them common to the various computers?