Mine is also a bit blue at night, and it seems even more so when contrasted with f.lux running on both my iPhone & iPad--that gives you MUCH warmer tones on screen at night (jailbreak required for f.lux).
However, the "blueness" of the PW2 in the dark kind of fades from my consciousness quickly enough as I read. And it doesn't seem to keep me awake...at least, not more so than reading late at night does anyway!
I'd prefer warmer light aesthetically, but as my PW2 is otherwise quite good, I'm fine with it.