My nephew words for the company that handles the luggage for DME. If the bag didn't have the yellow DME tag, it should not have been pulled. The system is highly computerized, and every bag pulled is scanned and entered into the system.
If it's accidentally pulled, they will realize before it leaves the airport, as there will be no bar code to scan to log the bag into the system before it is put on a truck. If it was accidentally pulled it will be taken to the luggage office of the respective airline to be reunited with the owner. According to my nephew, maybe twice a month this happens. Usually they realize the mistake while the luggage is still being sent to the carousel, and the owner never even realizes it had been accidentally pulled. They are more likely to miss a tagged bag then to take one without a tag.
The reality is that most likely either someone else picked up your bag thinking it was theirs, or unfortunately, it's possible it was stolen. Good luck.
PS--I would look to see if there is a similar bag still going around or sitting near the carousel that might belong to a person who may have accidentally took yours. If so, perhaps consider calling the phone number on the tag to ask if there might have been a mistake.