I definitely have the same problem - I can feel fine for awhile and totally trust that my heart is fine, then the chest pain comes back for a few days and suddenly I'm worried about my heart again! I had all the tests: multiple EKGs, bloodwork, and even an echo because they thought I had a valve defect. Everything was 100% okay. I also do CrossFit pretty regularly and have no issues with pain or tightness while I am working out.
Moral of that story is you're not the only one, but most likely neither of us have any heart problems to worry about! I find that if I can keep myself from panicking about it, I usually realize it's a muscle that is super tight and hurts when I move. So staying calm, while difficult, always helps!