Dad's best friend wants to date me

My dad died 3 months ago and since his best friend has been there for me. I'm 18 and his best friend is 52. He told me that he really liked me and wanted to go on a date. The whole thing makes me feel weird because it's like he waited until my dad died to make any type of pass. He was never like this towards me when my dad was alive. I've known him my whole life. I just feel so weird about everything and about him now.