People treating having a good memory as suspicious
A few people at work were talking about middle names, and someone asked me mine. I told them, then said to the person who asked me "yours is Claire, right?" She made a face. "And how do you know THAT?" She said, like I'd done something suspicious. I know because you told me! Like, two or three weeks ago! We've actually all had this middle name conversation before.
This is all things pretty minor, but it's an example of something I encounter fairly often, and it drives me nuts.