Without seeing the snake it is a difficult thing to determine. however, I am going to take a step back and tell you what an old herper told me when I asked the question. "Common names are "BS". they change from town to town." That being got out of my system...Roughly put...Eastern USA=pinesnake, Central=Bullsnake, Western=Gophersnake. Color variation can occur in litters or various populations. Intergrades are extremely common in nature where all species meet. Plus the other great devil popping up...all the designer breeding (Pinexbull etc... plus pattern and color anomalies) is further obscuring the lines. Many hybrids out there look so close to one or the other of their parent species that it makes it almost impossible to key. I'm bringing this up because you bought this at a show. If it were wild caught this would be simpler. Try to post a photo if you can....Frank