is it the derailleur or the shifter?
 

a couple days ago i took my handle bars off to see how they compare with a ligther set. when i put them back on and reassembled my bike i noticed that when ever i press the button on my sram x.7 shifter to downshift that the button doesn't pop back up any more for some reason. i have to manually push it back up.

what could have caused this? the cables look fine. is it the derailleur? the shifter?

If everything worked before, I'd say there's a good chance you've put something back together incorrectly.

Riser bar? Sometimes shifters bind up if they're located on a riser bar bend. Incidentally, your problem is certainly in the shifter rather than the derailleur.

what could be doing this though? they're not on a bend. they're a good couple inches from the bend.

Just covered this type of problem recently:

http://www.bikeforums.net/showthread.php?t=424766

my cable is tight. everything works fine except that button doesn't automatically depress. i guess i'll try disconnecting the cable.

I think the cable isnt seated in the shifter correctly.

works now. i guess it didn't like the angle i had my shifter at.