Can you're heart stop at anytime, or dose it need to have an issue or major proplem for it to stop???

Sudden death. It needs to have a major issue however some major issues are so subtle and first symptom cloud be sudden death in some diseases. ..
Always a reason. If your EKG and physical exam are not worrisome, and there is no family history of one of the uncommon sudden-death genetic diseases, just stop worrying. It won't happen unless you get major new disease -- heart attack or myocarditis. Get on with your life and cherish each day.