Is it normal for my classmate to look at my dick while i get dressed?

The last couple of times in gym class I noticed my class mate trying to take a look at my dick. I didn't think anything the first time but now it's like he makes the effort to catch me changing or getting dressed. I told my older brother about it and he said not worry about it and he's probably just curious and that all guys sneak a quick peek sometimes. I asked my dad he agreed with my brother but he thinks that he might be gay or that maybe he's never seen an uncircumcised dick before. My dad says as long he doesn't try to grab it then don't over think it.