A really disoncerting experience on LinkedIn. Thoughts?

I was just on LinkedIn and was quite shocked when I saw a suggestion to connect with someone I haven't heard from in about 9-10 years.

- This person was a friend from a community college course I took in high school and have not seen or spoken to since. - My LinkedIn email has no correlation or correspondence with either the community college or with him. I know LinkedIn has a history of pilfering contacts, but I use a business email that wasn't even created at that time. - I don't even mention on the site that I took a random robotics course at a community college or was even enrolled there. - There are no mutual connections.

So how in the world would LinkedIn think I know him?