Touching injection spot before giving needle?

I've had a few times when having bloodwork at the same medical lab where: the nurse swabbed the spot, rooted around the desk for stuff and then poked the vein at the injection spot with that same hand that was rooting for things on the desk, just before injecting the needle. I ask every time but they all say that this is the way they have to do it. Should I be concerned and if so, who do you complain to?