I didn't know what these were, so I looked them up. I get them, my mom does, and so does my 2 year old, I just never knew the name of them. My doctor and my dermatologist has told me they are completely normal and not to worry about it. My mom's doctor and dermatologist said the same thing, and no, they are not the same. And, my pediatrician said that it can come from a viral infection and not to worry about it in kids. If the blood work is coming back normal, I would quit stressing. It is probably nothing, but fair skinned people do tend to have them more.
I looked like I had the measles the whole time I was pregnant because I threw up so much! My mom gets them all over her abdomen, and so does my son. But, we are all completely normal and fine. I hope your son is too, but he probably is as there is no reason to think he isn't.