If your engine needed 89 or 92 octane new, then that is what you must run. If it didn't need 92 new, and does now, look for a problem. Your comment, however, about altitude was right on track. Now on the subject of a properly tuned engine pinging. Yes, they should ping, a little under certain conditions.
Engineering is a field of compromise.
You want the most power, the best fuel economy, the cleanest emissions, and the longest longevity out of any engine. But each of these conditions requires different tuning, generally opposite from each other. An engine needs to be tuned to operate at a sweet spot that is the compromise of all requirements. As I said earlier, pinging can be the result of high combustion temps, and this is the type you would expect to occur. High temps are caused by a combination of lean fuel and advanced timing.