Line at bottom of pin-it button

Hey there. I’m having sort of an odd issue. I designed by pin-it button as 120px by 120px with a transparent background (in Photoshop CC 2015). I uploaded to WordPress media library. I then used that URL to paste into the plugin’s visual section. Everything looked smoothly, at first. On my Featured Image, the button looks fine, but in an image added in the body of the post, there’s a line at the bottom of the pin-it button. I thought maybe this was an editing error as the whole circle took up the whole 120px in all directions, so I went back into Photoshop to change the canvas size to 130px by 130px, but left the button background the same size. I reuploaded and went through all the steps, only to find that the line still appears at the bottom of that second image. The post is still in draft mode so I don’t think anyone can actually see in from their end but here are some screenshots. The first is of my featured post image, and the second is the second image later in the post (using to be pinned to Pinterest).

Thanks in advance for any help!