The Scouting Combine is a time for NFL teams and prospective NFL players to get to know each other. It's like speed dating, except one person has watched extensive video tape of the other person.
Teams are allowed a certain allotment of 15-minute interviews with players, but they are also allowed to just grab guys who are milling around the media area to get in a quick conversation. According to OSU FB Zach Boren, that's exactly what the Bengals did with him, stating in an interview that he has met with representatives from the team.
More than likely, this is just due diligence on the part of the Bengals. The team already has three fullbacks on the roster (Chris Pressley, John Conner, and Jourdan Brooks), two of which have experience as starters in the NFL. Boren also stated that he had met with representatives from other NFL clubs, so it would be premature to start trying to connect the dots to Cincinnati. After all, most teams at the combine will meet with most of the players in some fashion, and the Bengals are likely just trying to cast as wide a net as possible.