White pupils in eye with camera flash???

Has anyone else read the article where a mother discovered her child had retinal cancer when she took a picture with a camera flash & her child's pupil was white in the photo? I took a picture of my baby a few days ago & noticed his pupil was white. I then took about 20 more pictures in different lighting & they were all normal. So I stopped worrying. Then today I was taking more pictures, similar angle & lighting, & his pupils were white in about 6 pictures.

The article I read did say that a picture is not a sure way to tell your child has anything wrong with his eyes. Also that it can be normal to take pictures where one or both pupils look white. All the same, this terrifies me. I took other pictures straight on & his pupils look normal. It appears they only look like this from this angle. Has anyone had any experiences or concerns with something similar? My nurse friend said she had never heard of it & not to worry, just to bring it up at next appointment.