Is it normal to think about cute girls i see in public all day long?

When I see a cute looking girl/young lady in public (which happens alot), I think about her all day and can't really concentrate on anything else. For example today I saw a very cute girl on the train she was probably around 23 and she had the biggest cutest eyes and I couldn't stop thinking about her for hours. Last week I saw a beautiful young girl on another train and I think she was probably the cutest girl I have ever seen in my life, she was putting on earmuffs and a scarf because it was cold outside and she looked so adorable and she pulled her hair back to put on a winter hat and her forehead looked so cute and soft I just wanted to kiss her forehead and the rest of her face. I can't forget about her no matter what.