If you were working out at a high enough intensity, I could see that being accurate.
Be sure to go in and update your user settings on the HRM if you haven't already. Your readings will vary depending on what you enter for your gender/height/weight.
"There's no such thing as failure. There's only feedback. Stop judging yourself & start recognizing it for what it is, an entry point for learning. The truth is, if you're not failing then you're not really reaching & really trying. If you don't like the outcome of a situation, learn from it, make corrections & reapproach wiser & stronger until you achieve your goals."