Is it normal to be turned on by elderly men

I'm 19 yo woman. I'm at collage and I do charity work delivering meals to elderly people in their homes. So, this one elderly man was always complimenting me on my looks and then after a few visits, asked me to help him masturbate due to his arthritis in his hands.
After a lot of persuasion, I agreed and ever since then I've done hand relief a few times for him, but now I get so turned on by elderly guys, especially this one man, that I'm thinking I'm a bit weird to feel this way. Does anyone out there think it might be normal to feel like I do?