I've got anti bodies for Hep A, B, & C in my blood.
A lot of vets of my era do, the thinking is that it's tied to the mass pressurized injections we got assembly line fashion. I don't know if, or when, they did away with this method of inoculation, but I got a bunch of shots upon entry, another round before leaving for Nam, one round at the 6 month point, and another round before they would let us come back stateside.
The VA did test me for the Hep C virus at one of my routine yearly blood draws, I am negative.
I have had several civilian and VA docs tell me the antibodies in my blood just mean that I was exposed to the viruses at some point in my life. Not to worry about it.
To humor the VA, when they asked me if they could check me for HIV I told 'em yes. Negative, of course. (I fit none of the HIV exposure guidelines).