Not quite true... A twisted limb is fairly easy to fix but if it's actually bending different (Like bending noticably more for example) that is likely another issue. But before you get bummed out, a twisted limb often appears to bend different so you may be in luck.
Sight down the bow while it is unstrung looking from tip to tip. Line whatever tip is closest to your eye up with the center of the limb or the cutout for the shelf and then look past it at the far tip and see if it is off to one side. Sight from both directions to verify.
The "sight picture"will look kinda like this:
|^|
|
|^|
if it's straight....
And like this:
|^|
|
| |^
If it's badly twisted
The two side lines are the sides of the limb at the widest point, the inverted "V's" are the limb tips. The middle vertical line is the site window cutout.
Crappy graphic, but maybe you'll be able to get the idea.
If only twisted you can do a search here on how to fix a twisted limb and you should find lots of info. Might even be a topic in the how to section.