Photoshop is set to display square pixels, by default. It sounds like you might be on a wide screen monitor that is stretching the display of the image. I use a CRT and it’s slightly distorted.
Which is to say, if I make a perfect square in Illustrator or Photoshop, than actually place a ruler on my screen. The square doesn’t display as a perfect square, but it would print perfect.
To my understanding, Pixel Aspect Ratios other than 1:1 are for video. Was this photo ripped from a video file, or are you intending to add this photo to a video?
Otherwise, I think the image is likely fine. Try printing it. If the printed image looks as it should than you’re probably just seeing a display distortion.