Baby measuring a week behind

So I am 37 weeks today with my fourth baby. All pregnancy I've been measuring normal but today I measured small so my Dr ordered an ultrasound to check on the baby's size. In the ultrasound I could see all the measurements coming back at 36weeks. I've gained plenty of weight this pregnancy and have been eating normally and feeling just fine. I think I read earlier this morning someone was having an earlier induction for their baby measuring small, anyone else have their baby measuring small at the end of pregnancy? I'm not talking they're uterus measuring small but everything was fine, I mean the baby itself was small and then what?