im pretty sure you should of babied it for at least the first 100-500 miles.. im no expert but it just seams like common sense for anything on the drivetrain to require a break-in period + these diffs are already under built as it is,After 4 long hours of hard driving & dogging my rear,I'ma say it's straight especially with no whine.
i got my replaced 2 weeks ago and am still babying it around but then again im out of warranty so i have a different mind set