well at first Sonny was acting up...he didn't want to go, and would NOT collect himself...so I was thinking that the saddle did not fit afterall and that was his way of telling me.
So I got off of him, and checked again to see if the saddle did fit, and again it still appeared to. So then, I realized something that I didn't at first...or at least didn't think it would bother him.
Since my pathetic nylon briddle didn't work with the western bit, I had to use one of the barn owner's briddles. Well that briddle (though it was western) had a noseband with it (someone added the noseband)...so I took off the noseband and added a chain to the bit (I didn't have one on at the time) and the minute I got back on him, he was great again.
Funny that a little thing like a noseband can make a horse so unhappy haha.