I changed strings today and found lowE tuner loose on my American Deluxe Strat.I tried to tighten but had to put a second shim under the nut to get it to tighten enough. This is a brand new strat and the first time i had strings off.
Anyone seen this before?

Anything is possible! I would inspect the barrel nut that secures the post through the headstock; perhaps filing the open end a bit would prevent the need for the shim washer.

If it really bugs you and it's still under warranty, take it back and exchange it. My guess is that if the part is not easily replaceable, the repairman will do exactly what I stated above.

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60th Anniversary AD Strat, Deluxe Nashville Tele, Player's P Bass. Mesa/Boogie Mk IV combo, Marshall JCM800, 1960A cab, Genz Benz El Diablo 60, Genz 2x12" cab, too many neat little practice amps and kit projects!