Does this happen to anybody else?

[G-Force Glockstar]

On my user options, I set it up that I get emails whenever someone replies to my thread or a thread I've posted in.
Anyways, sometimes it'll stop sending me emails for a while when I know someone has replied to my thread. Like my "My thumb is killing me" thread...two people replied to it, but I didn't get an email teling me it.
I went to sitcomsonline message boards to look at something, and I saw that there had been someone who had replied.
Why does this happen? It's very annoying to me.
Do you know what's wrong with it?
Usually whenever it happens, I start getting emails again a day or two later.

Please reply, I am really curious.

[Hollow]

because if you've already seen it, it doesnt need to tell you..