On Mon I went to the doctor, they did blood work on left arm, near outer bicep (right in the crease)...I trained arms yesterday, and when I got home, I noticed a light purple spot right where they took the blood...did I pop the vein? It's still there.
Some people reflexively flinch & tense up just prior to a phlebotomy, which often causes bruising.
Similar symptoms can occur if the tech drawing your blood needs multiple attempts to find the vein; it sounds like you were poked a few times.
Also, some people are more sensitive to developing the bruises than others.
You could always do what my uncle does when he gets blood work done: tell them if they don't get it in two tries, then bring over someone who can!
Some phlebotomists are less skilled than others, and some patients are harder to draw.
When both of the above scenarios are present, the patient will often end up a human pin-cushion.