To answer the question in your title ... not necessarily, but it can.
High Android OS with low phone use, particularly low display on time is normal.
High Android OS with moderate to heavy use with at least an hour of screen on time is not normal. This phenomenon is most attributed to a large amount of activity in the system's suspend and events/0 processes. I believe there is something about the stock ROM and possibly the stock kernel on all Galaxy SII class phones that can cause these two processes to run amok. Something about certain user environments can trigger the bug. The exact trigger hasn't been nailed down, but certain Apps (widgets particularly), whether an external SD card is installed, certain service syncs (Google, Facebook etc.) and certain email account configurations have been reported to possibly be attributed to it.
There's a couple really good discussions on the XDA forums on this subject here:
[REF][Rewrite 26/10] What the Android OS usage is and what it's not - xda-developers
Battery issue (AndroidOS "bug") - workaround (3% loss over 9 hours!!!) - final update - xda-developers
An App called BetterBatteryStats will allow you check your suspend and events/0 processes. If they're extremely high, then it could be a reason you're seeing excessive battery drain when your phone is supposed to be sleeping. Also, CPU Spy will let you see what CPU frequencies your phone is using. I would install it, then when your ready, clear the timers and set your phone down for the night. If Deep Sleep is not the highest percentage by far, then you may have a wakelock problem.
By the way, I've noticed that when I run a custom kernel (kernels compiled off the source code Samsung provided) my Android OS % is always tiny. When I run a stock kernel, it's quite a bit higher (although not to the point where it's a problem for me). Unfortunately, custom kernels come with the negative side effect of the Loss of Service bug, so it's a lesser of two evils scenario.