Green today?

I have been this forum for a few days. I asked about the 485 RFE waiting time last week. Today, I got the the email from USCIS, I was told approval notice sent for my 485. So my 485 RFE waiting time are 70 days.
I always heard from some other green people, USCIS normal tell you "your green card has been ordered, welcome...", Why didn't I receive this email? I was only told "approval notice sent", is that normal?
Thanks a lot for the support from this forum, Good luck to everyone.