Most people believe this to have first happened during the Flood years and 2012. But, it wasn't "really" the case. We had some verbal commits and they came back to Flood and told him they wanted to take other visits. He told them "go ahead, but I would no longer consider you a commit" - but, he had not pulled the offer. Their offers were still committable until they were filled by someone else but they were not held.
Most posters at the time loved the message - until they didn't- and then the story changed that Flood strong armed the kids and pulled their offers.
I also remember back in the mid GS 1.0 days- he often told recruits to take all their visits. Now, he wouldn't promise to hold their spots but he did tell them he preferred if they took them.