Hmm that sounds a bit high to me but having done pretty high level aerobic stuff most of my life I can’t say I have much experience of what is normal ‘off the couch’. So I would start by saying, if you think this is concerning then maybe shoot your doctor a message. They might say “yeah it’s no big deal as long as you don’t have chest pain or tightness” or they could say “yeah that’s concerning you should come in.”
So I would say the big things would be (as above) do you have any weird pain, chest tightness, difficulty breathing, or weird heart beat anomalies that you can feel? If you have any of those then I would definitely talk to a doctor. (Edit: just saw you have an appt next week. Absent these symptoms I would wait till then and mention it and say you just started a training program)
If not then it could just be a shock to your body. You say you are out of shape and overweight so you’ve basically just spent the last 12 weeks telling your body “hey, this is what we’re going to be doing from now on so you’d better start building all of the necessary infrastructure to support it.” So after working out your body is trying to replenish and build glycogen stores, repair muscle damage, build mitochondria, maybe even creating more red blood cells and blood plasma, maybe building new capillaries, etc. So all of that takes energy and oxygen so would require a higher HR to get all that stuff out to your body.