I think they do sometimes. When I entered my I-485 case number on Sep 20th it showed a message saying :
Application Type: I485, APPLICATION TO REGISTER PERMANENT RESIDENCE OR TO ADJUST STATUS
Current Status: We mailed you a notice requesting additional evidence.
On September 20, 2007, we mailed a notice requesting additional evidence and/or information in this case. Please follow the instructions on the notice to submit the evidence and/or information requested. This case will be held in suspense until we either receive the evidence or the opportunity to submit it expires. Once you submit the information and/or evidence requested, you will be notified by mail when a decision is made, or if the office needs something further from you. If you move while this case is pending, call customer service.
I guess not everyone gets that message. Which may be better in fact since I did not know what it was and had to wait a week to actually get the letter and know exactly what it was.
JNJ, from what I have seen on people's timelines, if sent express, next day, they can update in around 5 business days from date of receipt and resume a case.