No, having a heart attack feels more like "an elephant is stepping on your chest", not a subtle pain. And feel free to pop your sternum. It's like popping any other joint. However, if the pain is persistent or if the popping comes with any tingling or severe pain, that could mean there are some actual problems. Most likely though, you just did some chest exercises and could use some rest.
But to be sure: How long has this subtle pain been going on? Do you feel any pain, tingling, or other feelings when popping your sternum?
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence