Also, not sure if it is true, or not. But I've read somewhere else that the US Post Office has not been delivering letters from USCIS if your name is not on the mailbox. Apparently this happened to that person. However, I don't know if its true, but I just went ahead and added a sticky note with the names of the people who live in my house. Doesn't hurt.

Good luck on your process. May I ask, what city are you currently living at?