When you used crop you must have chosen a crop ratio in which you cropped your image. You can check more info on aspect ratio from Image->Resize->Image Size (it`s basically width/height or vice-a-versa depending on image orientation.
You can also check at our help link http://helpx.adobe.com/photoshop-elements/kb/crop-resize-resample-photoshop-elements.html to know more here.
Thanks for your reply. I should have noted that when I cropped the photos in PSE I did use the aspect ratio (in this case 4x6), and the photos look fine viewed in PSE, but when I then go to iPhoto and view the photos that I had edited in PSE, there the aspect ration clearly is off. Also if I view the photos in Finder, they are normal. Only when I view in iPhoto is it distorted. So maybe this is an issue with iPhoto, but I'm puzzled.