I made chicken stock recently from chicken thigh bones and skin (just needed the thigh meat and the bone-in-with-skin were cheaper). After cooling it in the fridge I ended up with gelatinous semisolid stuff underneath a layer of fat a few mm thick. I removed the fat, but am wondering whether the "stock" underneath it is useable for anything.
This is normal, expected, and desired. The long simmering of the bones will dissolve collagen in the connective tissue, creating gelatin, which will cause it to quite literally gel when cooled.
This gives the stock a body and texture that is considered a virtue in using it for soup or as an ingredient in other recipes. When heated, the gelatin will melt again.
As SAJ14SAJ said, chicken broth that gels is desirable. As a matter of fact, I break big chicken bones when I make broth to release as much collagen as possible and often add chicken feet because they're rich in gel causing collagen.
EDIT: America's Test Kitchen often uses "cheater" methods to skip some time-consuming steps but achieve the same, or very similar results. One such method I've seen a few times in their recipes is to add boxed unflavored gelatin (Knox or similar) to stocks and broths to achieve that luscious mouth-feel. What is Knox made of? Collagen of course, animal by-products. That's what makes Jello wiggle too.
Congratulations on your awesome broth! :)