He probably thought one or the other of you was cute. This tends to happen :\ In some cases, it's okay. As when your car gets shoveled out by a group of workmen who go "Oh, look, a female person trying to shovel her car out with a trashcan."

. . . Still embarrassing, though.

Either that, or he's one of those people who sees something from His Field and automatically thinks that means he Needs to Be an Expert. Everyone needs his help!