I have not listed any skills in my LinkedIn profile and I still get the occasional message from LinkedIn saying, "So and so has recommended you for Skill X! You

I have not listed any skills in my LinkedIn profile and I still get the occasional message from LinkedIn saying, "So and so has recommended you for Skill X! You should confirm this and recommend them back!" More irritatingly, I was recommended for Rails by a few former coworkers. I haven't worked with Rails in a couple of years now and I don't know Rails 3 at all. Their recommendation is legit: I was reasonably skilled in Rails 2 stuff back when I worked with them. But their knowledge of me is outdated.