For years and years, people did not wash their hands before going from patient to patiient drawing bloods. This is clearly not a recommended practice, however I am sure they did not touch the trochar, which is the only important issue. I would not be overly concerned. You might write a polite note to his/her superior, calling this to their attention.
You did the right thing by speaking up. More importantly, always question the need for a blood draw. Unnecessary blood draws in the elderly are a problem. These are usually done for insurance purposes. Blood draws are performed through a hollow needle, called as trochar.
I should have spoke up before the blood draw. I'm not his regular caretaker, my grandmother does that. I was just helping out that day. I'm just concerned that by her not washing her hands, she coukd have exposed him to something.
Report it to the people at where he went as it's a breach of their regs she can get a warning for it as like you said you don't know what is on her hands and maybe she isn't the only one who is doing that it can be a breach of health and safety