Or it means you had a problem and never knew it. Just because you think its ok doesnt mean everything is really ok! I had a 318 that ran "fine" I went to change the valve cover gaskets and found a broken rocker and a bent push rod that cylinder was completely gone it had been running on 7ish cylinders for God know how long. It never made a noise or anything. So i can see it to be possible to run a cam with used lifters and get a flat cam on one lobe or 3 and never know it and run it that way. I guess you would find out when you changed your oil tho. Maybe lol
