Don't know if this helps, here is the same general area on mine.
I will admit, that area concerned me a little at first also, but the dealer had other similar units, including a 2009 17C. They also had several new X17Z's, that waviness on the bottom trim was on all of them.
One of the things I do, if possible, is compare areas of concern with other similar units.
2013 Starcraft Travel Star 229TB
2011 Jayco X17Z(traded in)
2010 Jayco Jay Series 1207(traded for the 17Z)
2011 Chevrolet Silverado 2500HD Z71 CC 6.0L/3.73
Reese "Pro Series" 800lb Trunnion WDH w/sway control