mee too....
it its true, I noticed when new how quiet the engine was, I needed to step on the gas to know if it was running. then after about 2 months started to do that valve lifter clicking noise when cool, gone when warm, now at only 4000 mil. I can hear it even with a warm engine. so its getting worse.
It has to be some bad quality hydraulic lifters, or bad quality oil, or both. I'll go with my dealer to complain about it, and tell u what they'll do.
hope mazda do something about it.(flame)(pissed)