I wouldn't worry about it. Most likely, you knew or talked to someone who was pregnant, the soon-to-be-father, or someone else related to a pregnant lady. Perhaps a year ago she mentioned she would want a child or was working on having one but none came until you saw her recently. It's normal for people's memories of similar events to get a bit fused together and produce something that's incorrect. The reason is as great as our brains are, there's a limit as to how much content it can hold. If it were to hold every single detail of your life (i.e. including stuff you weren't consciously aware of at the time), your brain would overload. Instead, it filters content, scraps memories and fuses them together. There's a variety of cognitive theories that explain this in slightly different ways, chances are you're seeing one (or more) of them in action.