Baby measuring small at 32 weeks

So at my 20 week scan my baby measured in the 60th percentile and at my 28 week scan he measured 50th. All of a sudden at my 32 week growth scan yesterday he is measuring in the 15th percentile and my midwife said we would do a follow up in 4 weeks to make sure baby is still growing the way he should. They said he passed his biophysical profile with a perfect score and that he seems happy and healthy so they’re not concerned right now but 4 weeks is so far away and now I’m worried there is something wrong with my placenta or he’s not getting enough nutrition somehow. Has anyone ever been in a similar situation and how did everything go for you and your baby? Just feeling really worried and needing some reassurance. It seems everything measured smaller this time as far as head circumference, abdomen circumference, and femur length.