Actually, it's not quite that ridiculous. It would be ridiculous for a normal healthy snake to shrink, but I had one that had regurge problems for a while. When I measured her after about two months of her health issues, she seemed to have shrunk by an entire inch! I measured her three times, thinking I'd made a mistake, but I came up with the same thing every time.
However, since yours is shedding and feeding normally, I wouldn't expect it to have shrunk.