Laura, it looks to me like it didn't penetrate to the center. It is also a bit weird that it is so brown. It looks like from your picture that there is no off looking mold on the meat. It also looks like you don't have anything to encase the meat. Normally when I have seen this done, the meat is encased in beef bung or other casing. Umai Dry Bags also makes a membrane for sausage, dry aging, and dry curing. It keeps the bad bugs out and lets the moisture out, which is what you are going for. I assume that it doesn't smell "off" which is a sure sign that something is going awry.