I'm glad your HR returned to normal. For future reference, and because I've had a lot of not-just-anxiety heart stuff:
My resting heart rate is around 67 when I wake up, with low blood pressure. By the end of the day it's between 85-110. It is almost always anxiety/stress-related, and with my history of ED, sometimes dehydration. food and liquid intake can really impact your HR. spicy foods, and greasy, fatty foods force your heart to work harder. a large meal can easily take a totally healthy person from 75 to 120 for several hours.
Xanax and other benzos are HUGE for heart rate regulation. When i get close to my Klonopin wearing off, my HR goes up. If you're uncomfortable with a moderately high resting heart rate, ask your doc about beta-blockers. They take me from 85-100 to 70-60, and perfect blood pressure.
The thing is: this can fluctuate second to second. If you insist on hyper-vigilance with constant readings, try to do them a few times consecutively. If the first one freaks you out, sit and try to control your breathing with deep relaxation techniques for 15-20 minutes. keep the cuff on the whole time so you don't have to jump out of the relaxation to get a reading again. Get a reading -- it should be lower. If it's not, really just sit there and focus on breathing for about 3-5 minutes, and take it again. Wait a minute and take it again, if you want. If it goes up during this space of about half an hour, it would seem that taking readings is NOT helpful, and you should probably desist with those in general because they are contributing to your high HR. If it fluctuates, that means that your body is responding to anxiety and your attempts to control it. If it gets lower, congrats: you are taking control of your anxiety.
Maybe this perspective will help: if you're less than 40 years old -- you won't die of a heart attack. Especially from relatively mild tachycardia. It's just not going to happen. Unless you have a really significant underlying problem or are doing a lot of drugs. When I was severely anorexic and weighed about as much as a sack of lentils, doctors were constantly freaking out over my heart -- too fast, too slow, skipping, you name it. I learned waaay more about hearts than I would have liked. I developed mitral valve prolapse and other more serious arrhythmia things which went away after I got healthier. I had a friend in treatment who DID have a heart attack at 23, but she weighed about 68 pounds, and -- she lived. Bottom line: the body is immensely resilient. you are not going to have a horrible cardiac event if your pulse goes up and stays up in the mild tachy range. Nothing bad is going to happen to you.