How often do you get in the high rpms? Gunning it everywhere will give you 35. If your being conservative, you should be getting higher. My cbr600 gets 42 when gunning it and 60 when not. But I have a much older bike and your 636 is beefer.
Try this, go for a whole week without gunning it over 8k or so. Try not to get to the double digit rpms and see how your mpg is then. Also, try not to go full throttle either. I saw a high of 65 mpg once, but that was shifting nothing higher then 5k and driving like a granny.