I hear the occassional funny noise out of my MN6, but it drives fine. With only 1100 miles and a perfect break-in period so far (never exceeded 4000rpm, no stalls, no lugging in a high gear, and never seen 100mph), I really doubt I'll see a problem.
Maybe it'll just be a TSB that the dealers will handle the next time you come in for service.
To McGruff, no one is going to replace your tranny if it isn't broken. Drive it like you normally would, and if it breaks take it in for repair. If it doesn't break I hope you at least enjoyed the time you spent driving it.