Hi, so this may sound weird but I just wanted to ask if this has happened to anyone else because it just seemed very strange.

Last year, my dad went to the hospital for unrelated reasons and after taking an x-ray, they noticed something on his lungs. They told him to come back a year later so they could look at it again saying that, if it had grown a lot then it was cancer and if it hadn't then it wasn't. Am I crazy or is that weird? Is that normal procedure as far as you all know and/or have experienced?

Edit: Thank you to everybody who has responded. He should be going back to the doctor's soon which is probably what had this on my mind. You were all very helpful.