Weight Loss, concerning?

This is my second pregnancy, and with my first, I gained weight almost to a T how I was supposed to. Only gained about 25lbs. The entire first pregnancy. Started off at 148lbs. Though.

I am 31 weeks 4days, and I’ve lost 3lbs. In the last 5 days. My diet has not changed, neither has my exercise. I have never had morning sickness this entire pregnancy. So far I’ve gained 23lbs. Total my entire pregnancy. I started off at 123lbs. With my first, I gained .5-1lb. Every week in the last trimester like i was supposed to.

I just wonder if I should call by obgyn and see if this is concerning? 3lbs. In 5 days seems like a lot, especially when I was expecting to gain weight or stay at the same weight from here on out.