I agree with mls is that the girth could be dropped down a few inches. If it just as high on the near side perhap you should think about a smaller girth. Also I disagree with the statement that 34"-36" is an average girth size. I'm fairly certain, when speaking in averages, that 32" is the most common western girth size.
I agree with both mls and onetoomany, it really could not hurt to drop it down a few inches. I also agree that 34-36 is not the "average" size. I have a large quarter horse mare that takes a 32" just fine. I would evaluate the near side, and potentially purchase a smaller girth.
I was going to suggest a thicker pad for the too big saddle, but if that's the pad your using, I have the same pad so I know it is very thick and heavy. Its also difficult to get a good cinch down with it. That said you might try getting off and tightening up the saddle after about 30 minutes. It may be starting to slip and rub.