Your fingers know the truth.

I have been visiting my son Graham in California in recent days, and I left my fiddle behind in New Hampshire. I never would have done that if he didn't have a very nice fiddle, so I am not stranded without one. Every time I pick up Graham's fiddle, it takes me a while to play it in tune. It's not the fiddle; it's me. My left hand is just very used to my instrument, and though the two fiddles are set up pretty much the same, they are just different enough so that the "feel" takes some getting used to. This is nothing new. Any fiddle has its own personality, and it takes some time to get acquainted.