Originally Posted by
shepherdsflock
I really doubt that this is a chain crossing issue. That is almost non-existent with modern drive trains. It sounds to me like you've had some cable stretch, which is normal for a new bike that's still "breaking in". Take it to the dealer, have them adjust your shift cables and anything else that may need adjusted, and you should be good to go again for quite a while.
Certainly you could be right. However, it is a possibility. I have experienced this on a few 8 speeds and can only imagine the 9 speed would be the same (or worse). It tends to not like to stay in gear when dropping that low from the large or middle ring. Obviously, the nice thing about a wide range of gears is the overlap to make accommodations for this issue.
Anyway, just another possibility.