The dealers 'sounding' surprised is a total con. NeoDude, my car is the same model as yours, just 2½ yrs older.
I've had mine since Aug 05 and spent pots of cash getting a catalogue of common flaws fixed on it.
I recommend you look at the options in this forum and view my topics. You will see some pictures of rusty tailgates.
I'm not anti-Kia or anything, I can just see you have a few months left on your dealer warranty and if you trawl this forum you will identify many things to look into before the warranty expires.
Re your other comments.
1. "supa-guard" sounds like snake oil to me. If your wife is like mine, stone chips will be the least of your worries. The turning circle is so bad she had several near misses and one big scuff
2. Inky's comment may apply to his country, but in the UK any dealer can access full details via reg no or chassis no.
When you go to the dealers, let them start to bluff you about the tailgate and then catch them off guard by tellingthem you know its a very common problem.