Yesterday I cranked my car and letting it Idle to warm up, I was walking around and I could hear a faint tapping, but opened up the hood and couldn't diagnose where it was coming from after about 3 of 4 minutes it was gone, I had gotten on it pretty hard on Wednesday afternoon, the oil is good, this morning same thing, faint tapping, warmed up it's gone, hoping that I haven't hurt it, it has 50800 miles, any thoughts