I’ve added a custom social button for Yelp on miboxdallas.com. On planobarber.com, it is in the page sidebar and looks fine. However, on miboxdallas.com it is in the footer and is showing both the regular image and the onhover image. Eek!
Edited to add a little more information: on mobile, it just shows the gray image at first. When you touch it, it then shows the onhover image but does not follow the link. The other social buttons work fine.
Also, I added a sidebar to http://miboxdallas.com/why-choose-mi-box/discounts-and-special-offers-on-mobile-storage-containers just to test it, and the Yelp button works great.