That was supposed to be a good news. Everyone wanted Nebraska last year. Try to involve your Congress man or senator, it helps.They usually don't send notices of transfer, from what I've read on here though.
You can give it a couple of weeks. If there's still no movement, then I'll suggest you start reaching out to your senator/Congress man's office. Ours took some months after we saw that change in status before we heard from uscis.