Very professional sounding to my ears!

My only suggestion for change:
There were places where the mandolin and fiddle were playing nearly identical notes. Since the real track is outside your (total) control, but the mandolin is totally IN your control, it would have been interesting to hear the mandolin play harmony to the fiddle's notes.

But, if that's the worst problem you have, life is GOOD! eh?

You, sir, are a songwriter.