Recurring Granulosa Tumors

I had a granulosa cell tumor  removed by way of a total hysterectomy in November of 2002. All inhibin A and B tests have been in the normal ranges since then. Last month,  I had my physical and blood tests were taken.  Although the general practice doctor thought the ranges were normal, the cancer doctor who also received the results thought the 20 reading for Inhibin b was high and wants a retest by November. Since I have no ovaries or uterus ( also the tumor never ruptured and the pelvic gutters were clean after surgery), can this tumor reoccur? Where can it be generated from and where can it be lodged?
In 2003, one large and one small thyroid growth were discovered; neither was malignant. I also took synthroid until last fall.  Can the thyroid effect the Inhibin B levels?