After taking a look around the map, I see that most (if not all) props
have that sunset envmap while the weapons and world surfaces have the
correct cubemap reflections.
It happens to me quite often, and the method I described above (changing from mat_bumpmap 1 to 0 etc) ends up fixing it.
For example, when I run cubemaps in cs_fallingliquid, the windows might
get their reflections while the sinks and toilets still have the empty
sky as a reflection.
EDIT: Just as I thought. Here's a picture of the lockers with the
cubemaps Juim built, and the same locker with the same settings but
after I rebuilt the cubemaps and messed with the mat_bumpmap command.
(It might look like there are no reflections, but there are. They are
just not as obvious as before).
http://img405.imageshack.us/img405/6308/dmstoneparkalpha20000sw4.jpg