Was the user a spam bot? Maybe the bot saw a city mentioned in the group and generated a spam comment using that city. It's possible some people (or bots) from

Was the user a spam bot? Maybe the bot saw a city mentioned in the group and generated a spam comment using that city. It's possible some people (or bots) from Africa viewed your page and no one else did in the recent past, and thus Facebook thought there was some connection between you and Africa.