I wouldn't worry either, they are probably coming!
That being said, I know last year some people didn't receive a package at all. Someone on this board didn't get one, maybe Helen , they reassured her that she was registered and just show up at the expo to pick up her bib.
Lynnda never got her packet last year. She was a little annoyed with me about that for some reason. If you don't get it, you can still get a waiver at the Expo and tell you where to get your number. The packet is online this year so you can still see what is in it.
They send out the packets as bulk mail so the post office delivers them as they feel like and the times can be drastically different in places.
I received mine last week but DH just got his yesterday. We registered at the same time, have #'s right next to one another and they were both sent to hour home, so I would not worry yet.