I had my bag arrive early at DCA once, and in fact, it was about 3 or 4 days after it opened after 9/11. I was flying YVR-ORD-DCA, and it made a connection that wasn't legal for me. When my bag didn't come off the carousel, I went into the bag office to report it as delayed, and after filing the paperwork, looked outside and realized it was sitting just outside the bag office.

I know in ORD they have lockers between a few of the carosell's for unclaimed baggage, and that there is an agent to unlock it if you're bag is in there. I did have my bag in there once, though I can't remember the situation and why. However, I always wondered when they actually go through and pull the bags off if not claimed. At least on carousell's 1-6, they seem to be always being utilized for several inbound flights at a time, so unless they have someone looking at bag tags for specific flight numbers that landed, say, over an hour prior, there are always bags flowing on and off frequently.