I had back surgery a week ago and my blood pressure has been continually low is that something to worry about?

Get checked out. A number of things can cause low blood pressure following surgery, none of which are good. Blood loss can cause this, and if your pressure is low, it might signal you don't have enough reserve. Infections can also lower blood pressure. You should see your surgeon asap. If you are feeling light-headed or confused, you should go to the er.
Depends. It depends in part on how low you mean. There are a number of factors after surgery that can lower blood pressure to a mild degree including anemia and the use of pain medication. A check up by your primary care doctorate be a good idea. Thank you.