Change in BBT after IUI

I had an IUI on July 9. I have been taking my BBT for a little over 3 months now, my average BBT is around 96.5. The last couple of days noticed that my BBT is going up. 7/12 it was 97.2, 7/13 it was 97.7, and today 7/14 it was 98.1. Is there any reason behind this, it has thrown me off a little because I have never seen my temperatures this high before and I check my BBT religiously the same time every morning. Any thoughts?

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