Can a pig sense pregnancy?

I have a 2 1/2 year old inside pet pig and she just started nesting outside and inside today and has yet to do this behavior before. They say pigs nest when they are pregnant and we 110% know she isn’t pregnant. I haven’t tested this month yet I’m not trying to stress over it again so I’m just wonder if you guys think she can sense a pregnancy or I’m just over thinking it or if you’ve ever heard of something like this before? Thank you!