blender 2.68 is it normal when rotating an object, the edges become jagged?

when i rotate an obj, the edges become jagged it looks like a zigzag. the edges are no longer crisp and straight. thanks in advance

Too little info. We need a screen shot. or a blend file. It could be many things.

Is this in the 3D View, or in a rendered animation? Assuming the former, then it’s most likely that your 3D View isn’t anti-aliased. It’s not really a big deal. However, if you really want it, you can change the MultiSample setting in User Preferences > System (it’s in the center column). Fair warning, though: this might make your 3D View slower.