Miata front bumper curling, WTF

 So ever since I got my Miata, the front bumper’s edge is kind of raise and curled up just in front of the driver side headlight. I’ve read on the Miata forums that this is a common occurrence for the bumper to warp in other areas, but I have not seen anyone mention the bumper end curling up where it meets the headlights. As far as I can tell this car has never been in an accident. Is this a common occurrence, or unique to my car? I ask because I don’t want to put another factory bumper on and have it do the same thing. 

 Side question, will a 93 bumper fit a 97?

There are "rods" that run from the front metal bodywork to the corners of the bumper.  If those rods get bent, they curl in the corners of the bumper.  (It can also happen if the car is in an accident or driven up on a curb)  The good news is that often straightening out the rods removes the curl from the bumper. 

So the driver’s side “rod” was disconnected. I found that weeks ago and reattached it. Nothing has changed since then. I’m thinking used bumper. All NA bumpers interchange?

As far as I know, yes.  All NA bumpers should be interchangeable.  Just be sure the rod you re-attached is straight.  Whatever knocked it loose probably bent it as well.  If that is your issue, it will pull a new bumper out of shape as well.  Mine was curling exactly as you described.  When we did my re-paint, we bent it back straight with a brick on one side and small sledge on the other.  Viola, straight bumper.

In reply to kazoospec :

So you removed the bumper to address the ski slope on the nose? To the garage I go!