Logo Distortion

On my website, http://www.scmodeltford.org, our logo in the top left corner looks fine on the home page, but is flattened and distorted on the rest of the pages. I have no idea why. It only started doing this about a month ago, and the site has been live for a couple years.

I am using Customizr theme and find it very user-friendly, but this problem is annoying.

Any thoughts?