From my personal experience, I believe when they ARE slightly uneven they produce the best sound.  When they are perfectly lined up, you seem to get an "air" sound.

The bottom line is, whether the felt on the bottom wears out, or the hi-hat rod is slightly bent (which most are) your hi-hats will always be uneven.

In fact, I like mine a little uneven both vertically and horizontally, so I use the little adjuster on the bottom hat and tilt the bottom cymbal slightly.  For me, it gives really good results.

call the customer service and see if they can help you out

oops... its not bent its warped, i jus found out wat that means lol... im gona start another thread on this specific problem