H1B visa case status changed to acceptance status from post decision activity.

After my RFE response on 3rd October MY H1B status got moved to Post Decision Activity. But after 3 days my H1B-Visa status is moved back in Acceptance stage.

On USCIS website I can see the message “On October 6, 2014, an amended notice on this case was mailed describing how we will process your case. Please follow any instructions on the notice”.

Could you please tell me what will be the reason behind it, Is it glitch from website. I am little bit worried beacuse it has been 23 days from approved activity and I havent recieved petition yet.