What type of device and email client are you using when you see the elongated images? I don't seem to be able to replicate that on my device (iPhone 7 Plus in iOS Mail).
I checked your two most recent mailings using Litmus Inbox Preview to see how they would render on a variety of desktop and mobile clients, and I'm not sure I see it there either. You can view these results here and here.
Keep in mind that it is expected behavior that the 3 images you have beside one another horizontally will stack vertically on a mobile device for optimal viewing.
If you have a different mailing that you'd like me to look at, please indicate that here and provide a screenshot of what you see, if possible!