Apple Watch 6 - red burn mark on wrist from the sensors

Has any one experienced developed circular red burn marking on wrist while wearing the series 6 apple watch? I noticed this marking after running on the the treadmill for about 45 minutes. Took the watch back to the Apple store and they will escalate case this to their Safety division for further examination. I have worn the watch everyday for a year and have not experienced anything like this so think I can rule out allergies/allergic reaction.