A resting heart rate over 100 is not exactly normal, but a lot of things could be causing it. A high thyroid level could make your rate higher, but usually comes with wt loss, diarrhea, temperature sensitivity and shakiness/tremor like feeling.
However, a heart condition all by itself can do it, as well as things like dehydration,anemia, fever, and other hormone issues.
The most common cause if it goes over 120 and then back down, is anxiety. In addition, being overweight and "deconditioned" is another reason for a faster heart rate at rest.
In either case, it is something that you want to see a doctor about. Certain tests can be done by the doc right there in the office to eliminate factors. An EKG and Bloodwork is likely necessary (including thyroid levels) as well as a complete physical.
No reason to panic, unless you have chest pain, shortness of breath, or dizziness. In these situations, I would recommend the urgent care setting. If none of these,
I would simply call the office in the AM and make an appt to be seen.
I hope this answers you question- feel free to redirect on any point as needed.