was told at 23 weeks that baby has dilated kidneys!!

I went for my 23 week dr visit and they told me the results from the big 20 week ultrasound. Apparently my baby boys kidneys are dilated. Normal range is .4 and a worrisome range is .8.   My boy had .6 and my dr said don't worry it usually clears up on its own but it's my first I can't help but worry. I would feel so much better if anyone has experienced this and had healthy babies. Thank you!!