The law in Tennessee is completely different. As long as you have your permit, you can carry the gun loaded and, if it's a semi-automatic, even have one in the chamber (as long as you have a decent holster, I recommend this; you don't want to have to fiddle with loading your gun during a high-stress defensive situation). Also, Tennessee's law makes no distinction between open and concealed carry. You may carry openly anywhere that you may carry concealed; and you cannot legally carry openly anywhere that you cannot legally carry concealed.
Also, you mentioned that the clerk didn't seem to notice. Don't be surprised. You MIGHT attract some attention in the big-4 Tennessee cities (Knoxville, Chattanooga, Nashville, and especially the liberal-leaning Memphis). Anywhere else, don't be surprised if 95% of the people you meet don't notice and another 4% notice but don't care, leaving only 1% that notice and care. Of that 1%, many of them will actually complement you on it, ask out of curiosity what type of gun it is, etc. Only a very small number will give you what I call the "stink eye", or panic and call 911 with what's referred to around here as a "man with a gun" call (or woman, as the case may be). As far as me personally, I can count on my hands the number of people that I know for sure have noticed it; and I've carried it around probably a few hundred people during the length of time I've openly carried. Also, so far, I've had only one MWAG; and that one was resolved very quickly after showing the officers my permit (if you want to read about it, go to the "TN Open Carry Report" thread that is stickied at the top of this board and read posts 195, 196, and 197).