Unfortunately yes, this is a common malady. My 05' suffered from what many call the SMOD - aka, the Strawberry Milkshake Of Death.
This name was given as a result of the color and texture made when the AT fluid and the engine coolant mix. A frothy pink substance which looks eerily similar to the fast food confection of the same name...although not quite as tasty and much more expensive.
The first thing you need to check on the dealer paperwork is to make sure they installed Matic S AT fluid in your new transmission...NOT the old Matic J fluid.
The Matic J was responsible for the slow internal corrosion and eventual failure of the transmission fluid line that runs inside the radiator of your Xterra. That is why Nissan covers this repair and extended most warranties.
Like the others said, do a quick search over on thenewx.org as well as Xterra Nation to get more info on the radiator bypass, as well as other transmission related DIY maintenance tips.
Good luck...us 05's gotta stick together.
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