Back in 1987 I was buying bred heifers, just starting out to build a cow herd.   Ran something like 20 head in the ring, I took 10 at gate cut, paid $700 a head for them.   Offered the rest to next highest bidder and he declined, so they started over.    Remaining 10 brought $50 a head more, same weight and quality.   The seller and I had a good laugh over it about a week later.   Apparently someone woke up and wanted them and I've seen it happen a few other times over the years.