If the VIN says it is a 2005, then it is a 2005. I agree with you that it sounds like it was just a typo on the temp tag. In the spring of 2011, I bought a new Blue Ridge 3705BH fiver that was built in March of 2011 and sold as a 2011 model year trailer. However, they had already started gearing up to build the 2012 model years when it was built, so I got a 2012 paint scheme that looked much nicer than the 2011. Trailer manufacturers aren't real predictable on their color schemes, lol.
Mike in Tennessee
2007 Cruiser 30QB
2008 Ford F250 Lariat 4x4 6.4 Powerstroke
Valley 16K slider
Ride-Rite air bags