Why does my notification light blink when I have no notifications?

[AC Question]

I have an HTC one m8. I have recently gotten a new one after my old one stopped working. However, after receiving the new one (it was a replacement from my phone company - I have T-mobile) I will often have the notification light blink when I have no new notifications? It isn't that it isn't showing the notification either, there just isn't one.