I rely on the red LED light when I have new message, BIM, or whatever.

Although not often, but I have seen that the red LED did not blink, and when I "wake up" my Tour, I find several new messages.

Fortunately this did not happen too often, but it is sometimes annoying.

Did that happen for you too?

The red LED only blinks for "new" messages, not "unread" messages.
It won't blink forever. After 15-20 minutes or so, the LED will stop blinking.

You can change this behavior with third-party software.