TSH drop?

I've been diagnosed with hashimoros for about 3 years now. In that time my t4 levels have been roughly consist at the low end of normal, while my TSH has been steadily rising. Neither have gotten to the point of being out of the normal range, so I am not on medication yet. I just got my bi-annual blood work and my TSH made a major drop, from 3.58 to 0.98. I do not yet have my t4 back.

While it was just my routine blood work I have recently noticed I've been incredibly fatigued and my skin has been extremely dry.

I won't get any input from my Dr until Monday, and this sudden drop in what was expected to still be slowly rising has left me concerned and confused. Not looking for medical advice of course, just would appreciate any thoughts anyone has.

TL;DR: TSH has been slowly rising the past few years as expected, but has not dropped from 3.58 to 0.98, why??