Is it normal to miss somebody you were never close to?

I graduated high school in June. I went to a very VERY small private high school - 18 in the graduating class. Only 70 or so 9-12th grade. I probably would only ever see... maybe 5 of them at any point in the future. But even those who I didn't talk too much, plus some out the the class that left before us, I look back at their facebook pages and miss them, even if we barely talked! Maybe it is more an unsettling feeling that I spent years with these people and then suddenly, never see them again for the rest of my life. But, IIN?