Video232 -- Please keep us all posted on what Sig says when you call -- I think you are on pretty solid ground for a claim:

1. New Airplane -- assembled with the assistance of a LHS that I presume is a Sig dealer.
2. You were flying with an instructor who is also the same Sig dealer
3. You have a great photo documentation
4. As previously said is a very reputable manufacturer

I learned to fly on a Sig Senior Kadet earlier this year and absolutely love the airplane. I also gave it a fair share of abuse and it is a pretty strong airplane and still flying every week. I liked the Kadet Sr so much I have since purchased a Rascal40 arf, 4*40 arf, and am building a 4*60 kit as we speak. Needless to say I am a big fan of Sig and would be disappointed if they did not make it right with you.