Am I overreacting about a picture posted by a female co-worker of my husband?

My husband and I work together. A female co-worker who my husband interacts with regularly has a picture of my husband and his father posted on a wall in her cubicle. The picture was from a fishing trip that my husband, his father, and two other male co-workers went on. She has other pictures of other male co-workers on the wall as well. Before I started working at this company, my husband and this co-worker dated briefly. She is married with children.