I have a 2004. I experienced the problem back in 2006. I had the belt replaced under warranty, the tensioner checked out ok. The problem returned shortly after. Using information from this site, I discovered the 2004s had a problem with the crankshaft pulling bolts backing out. Evidently, blue locktite was not used during the assembly process on some of the vehicles resulting in the bolts backing out. If not caught in time, it can lead to catastrophic damage. I visually checked the crank pulley while the vehicle was idling and could see a slight difference in its position relative to the other pulleys. It was very negligible, but it was there. I returned the vehicle to the dealer which found the bolts had indeed backed out and fixed the problem under warranty. This may or may not be the issue you are experiencing, but it would be worth verifying that it is not.
As stated above, I learned about the problem from this forum and it was valuable information. If you have a vehicle latter than 2004, it should not be a factor as I believe the manufacturer corrected the problem; however, keep in mind, people are people, and if what ever device used to put the loctite on is low on product, the norm is try to make it last as long as possible resulting in less product coating the threads before new is added. Kind of like trying to get every last bit out of a tooth paste container and settling for a smaller than usual amount. It could come down to something as simple as being low at the end of a shift and the technician not wanting to stop in order to finish what he/she is working on. My advice, check it out. Make sure the crank pulley is correctily in line and when running there is no wobble or drift out from center. It does not take much to generate the squeal. If it is continuous, there is a problem which, left unattended could you leave you walking at some point. Good luck tracking it down.