Hi, In The Last Month I Have Awakened About 3

Hi, in the last month I have awakened about 3 times in the middle of the night with my heart pounding as if I had been exercising, after a few minutes, it settles back down. No pain, shortness of breath, or other symptoms, and I go back to sleep.
I am a 71 yr. old male, in reasonably good health, 6'2", 235 lbs. I play tennis, work out and I think I am pretty active for a geezer. What do you think?
Gary