Coming from TextMate, this is an unresolved problem there as well.
If you take the following bit of code...
var valueUnit = parts || ( cssNumber[ p ] ? "" : "px" );
...and start to double-click then drag to select it, Sublime Text 2 gets overzealous when selecting whitespace. If you repeat this process here on the forums (in just about any browser) the behavior is more desirable.
So far, loving ST2 aside from that!
Customer support service by UserEcho