Café au lait spots

Hello all. I am a new mommy. I have two twin boys. Delivered last month. They are officially one month old as of yesterday. I just wanted to make sure my son was ok. This is Zion and he has these spots on his lower leg in the back. The dr said it might be a birth mark and that just to watch it to make sure it doesn’t spend or get any bigger. I am praying it is just a birth mark. I and the father do not have any neurofibromas in our families. What does this look like to you all? Has your baby or babies ever had this before? Let me know. Thanks.