Concerned, yes. Of course, it is possible that some of your interim activities (including associated breathing) may have strained neck or chest muscles to produce similar symptoms. It could come from swimming or biking into the wind with a helmet on, but the symptoms are close enough to possible cardiovascular symptoms that it is too close for comfort.
I’m also in my sixties, and if I push too hard with speed or distance, especially in the heat, I occasionally experience chest tightness. It goes away after I back off for a while, but if I had the exact symptoms you do, as consistently as you report, I would schedule a visit with a doctor. Heart rate alone may not be a reliable indicator of a CV problem.
If you are cleared to resume your training, you will not only be able to train more effectively, but will train with greater peace of mind as well. Best of luck!