It cold be a lot of things . . . or it could be you're on the verge of a heart attack. It doesn't have to be actual pain
I had chest pressure - pretty minor - a few years back. Decided it couldn't hurt to see a cardiologist, even though I walk a few miles daily, do weights, etc etc. He had me back the next day for a nuclear stress test, and the day after that I was on the table having cardiac catheterization and some stents installed.
Turned out I had less than 1% blood flow in my widowmaker artery (left anterior descending).
I wouldn't advise ignoring unusual sensations in your chest, especially if over 50 (or out of shape at most any age)