From MrRed's post: Ian Bruce reckoned he picked-up the wrong guitar one day and launched into a tune.

I have done almost the same thing - picked up a guitar that I thought was tuned in Open G and began playing an Open G piece I had recently written - only the guitar was tuned in DADGAD - and it worked - got two tunes for the price of one.

Maybe you could cross tune your fiddle and tell your fingers it's still in standard tuning and see what comes out.