Fibroid tumor came and went?

I recently had an appendectomy. After my surgery, the general surgeon told me he found something during the surgery and was concerned, so he called in an OB. The OB also saw it and diagnosed me with leiomyomas disease. They both agreed that I have developed a fibroid tumor. The OB wrote up a report stating it was a 3cm tumor in the right broad ligament, and I would benefit from a hysterectomy. I followed up with my own OB, who read the report and ordered an ultrasound. I went today to have the ultrasound and the tech looked and looked and looked, and no tumor. Anywhere. Nothing. Is it possible it disappeared or that the original surgeon was seeing things? Or the tech missed it? I am not really having any symptoms, no heavy bleeding, no irregular bleeding, a little crampy now and then, but we've sorta chalked that up to the poking around during the appendectomy (which was one month ago). Thoughts?