No it isn't a bug, it is an initiative put in place to combat spam (frequent) posting from newly created accounts. Like the notice says, the more establish your account is (higher your rank), the limit decreasing. so for now you just have to wait for another 360seconds that's 6minutes to make another post.
If you clearly read my main topic, I was obviously aware of the 360 second limit for low ranked users. My question was specifically about replies and reports being seen as one thing by the anti-spam system.