Has it been over a year since you had your piano tuned. Even if you haven’t played your piano it needs attention just like your car. Over time the pitch tends to fall evenly across the keyboard so you may not notice it being out of tune. I tune modern pianos to standard pitch (A=440), the pitch for which they were designed. My standard piano servicing includes tightening the bolts on the iron plate, adjusting the pedals and a standard tuning. A pitch adjustment may be required if the piano is far out of tune.