Whether a 10w30 stays in grade or a 10w40 degrades to a 30weight, doesnt matter they both are now the same grade, and both the same. Its just that you started off with a Higher fim strength in the beginning.
Sounds like this was the first oil change in the bike, thats alot of miles for a high performance motor, I generally only go a few hundered miles on a break in.
My only beef with 30 weights in mc motors, is 30 weights dont supply a strong enough cam lobe wear film if turning alot of RPM, This was my lesson running oils in the 30 weight range. Car motors only turn 30% of the rpm, so 10w30 is less an issue in them.