I would highly doubt it had anything to do with your being in ratio or not. if he knows one of your DC families then I would assume he was taking a picture for them, either because he though they might like it or because they expressed some concern to him. Or he liked the flowers you have in your garden, or a toy you have out front...or he's just a creep.

I would think it could be many many things before I would assume he feels you have too many kids and he wants to report you!