Odd...

So today I'm 38 weeks and had an appointment with my ob. He listened on the Doppler like normal, measured my belly which up til 2 weeks ago I was measuring on track or ahead by multiple weeks. Then checks my weight and I lost 3lbs since last Friday. Nothing in my diet has changed, my activity level has decreased, and I haven't lost any fluid or anything. So I'm not really sure why the loss/small measurements..... Dr says he isn't worried; just surprised. And nothing "feels" wrong. So idk. Just shocked I suppose.