Uneven calves at 35 weeks?

I’m 35 weeks and had the genius idea to buy knee high boots to go with my baby shower outfit this weekend. They fit perfectly when I first tried them on about a week or two ago and thought I was fine. I haven’t had any swelling throughout my pregnancy. Anyways, I tried them on today and one of the boots now wont zip all the way up There isn’t a visible difference but the calf that can’t clear the zipper is clearly now bigger than the other.

Has anyone else had this happen? I feel fine but should I be concerned?