Circle not marked as "read" if I come and go too quickly

1. Often but not always (hard to reproduce), I go on a circle because it is marked as "unread".
2. I read the message that is there.
3. I hop on another unread circle.
4. I see the circle I just come from is bold, so I think: oh, someone just added something
5. I land back to see the same message I've just read a minute ago and nothing more

My conclusion is that sometimes, maybe because I go "too fast", the circle is not marked as "read" on the first visit. It it eventually properly mark as "read" on the subsequent tries usually.