Got Pre-Check today at IAD, and noticed two things new to me:

1) At the check-in kiosk, when printing my boarding pass, the screen told me to proceed to Pre-Check. Is the system now telling me I have been approved before I actually get to TSA? Thought the uncertainty was one of the precautionary 'features' of the program.

2) No longer using the scanner that reports using beeps. I got a green light. (perhaps red if denied??). I asked the agent if we are done with the beeps, and he nodded.

I get Pre-Check on UA via my GE membership, and have had a high level of success.