Rash / Allergy

Monday after Jerry's visitation, we went to Pasta House for dinner with my parents. We all shared our food with Kaitlynn and at the end of the night she had a red circle on her nose and on her cheek. It looked like a rash, so I thought maybe she was allergic to something that we gave her. The only new thing she had was eggplant, unless it was from the sauce or spices. It went away within an hour or two. Since it went away so fast, I don't know if it was an allergic reaction or what. I thought when a baby had an allergic reaction to a food the redness lasted for a few days. Any ideas?