Prednisone and post menopausal endometrial changes

I am 71 and was diagnosed with PMR about a year ago. Still tapering and down to 6mg a day and feeling well. It's been almost 20 years since menopause and I just had an ultrasound that showed changes-thickening and some cystic tissue in the endometrial lining. Also 2 episodes of slight bleeding. I will see a gynecologist soon for evaluation and probably a biopsy. My Rheumatologist says he's not aware of any connection between prednisone and uterine changes. Maybe it's because I'm just getting older but it's weird that I haven't had an issue in almost 20 years until taking prednisone. Anyone have thoughts or similar experience?