A While Back I Was Walking Home And I Saw

A while back I was walking home and I saw somebody was throwing away a chair. I needed a chair, so I took it home with me. When I got home I decided to clean it off with a rag, and I noticed there was something dried on the seat. I didn't think anything of it at the time. I cleaned it off. Anyway I've been thinking about it lately, and it may have been dried blood. Do I have a chance of getting HIV? I don't remember if I had any open wounds on my hands, and I rinsed them off after but I don't remember if I used soap or not.