Is it strange for a person to look up information about the child of someone they once dated?

My husband and I have been together for 4+ years. Over that time I have become aware that at least twice he has looked for information on social networking sites about the daughter of the lady he dated before he and I were together. They were together off and on for about 10 years. I maintain that this is strange to look up information about her daughter however he sees no issues with it. Both times I found out about it, he had sent himself pictures of her that were posted on her site...not sure if that makes it better or worse. Anyway, just looking for another opinion(s) on this.