I don't think this is normal. My SB waits for 10 seconds (not 4), and then, if the screen is not detached, it simply shows the green "Attached" sign again. No red light, no error message. I think that's normal.
The only time I have seen the red light on the detach button was when the auto-rotate function was not working, whereby the button would quickly go from green to red, and then I knew that, even though the screen would detach, it would not auto-rotate (or rotate at all, period). This annoying bug was fixed with the April updates.
I know that the detach button has a timer, and that makes sense in order to avoid inadvertent button presses, but I don't think what you are seeing is normal.
I would make sure that the contacts and hinge are clean and dust-free, then I would do a two-button salute (press power and volume-up together until the BIOS screen comes up, then exit and restart).