You know what, you're right!
I didn't pay attention to your 'actual' name, saying you have an '05 X.
I was stuck on the '00-'04 models.
You do have automatic tensioners.
In which case, the back of the belt is probably glazing, causing the noise. You might have a pulley that needs to be roughed up a bit.
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Hope line and sinker.
How's that hopey changey thing working for you?