My camry is approaching 64,000 miles and I seem to hear a noise developing that wasn't present before. It is a noise which varies with engine speed and doesn't appear to be a bearing noise. The maintenance schedule calls for checking the valve clearance at 60,000 mi. I would have assumed that the engine had hydraulic lifters but naturally I could be wrong. The other item that I suppose could make the noise would be the timing chain. The car gets regular oil and filter changes but I travel back and forth to Florida each year so I am naturally concerned. Any thoughts on the matter?