To ask the obvious, did you read the e-mail or the page that it sent you to? Not being derogatory or anything, I just don't know exactly what was in the e-mail, so it could have more instructions on what you can do.

I don't think it'll affect you at home. I'm not sure what suspicious activity they're detecting, but it could be something as simple as you logging in from an IP that's different from what you normally use. You might be right that it's just something with the open wireless connection.

Regardless, I wouldn't really worry too much about it unless it sticks around once you get home. If that happens, just go to that page, hit the 'additional assistance' button at the bottom, and tell them that you can't get the restriction removed.