Normal to lose a couple of pounds during 3rd trimester?

Lauren
At my last dr's appt, I weighed in at 169-170 (their scale couldn't make up it's mind) & when I weighed myself on Monday, I clocked in at 172 & after yesterday's walk (roughly quarter of a mile) & BM, I checked my weight today and I'm back down to 170. Should I be concerned? Baby boy is growing perfectly and is super active.