Yeah, I've also heard that tack welding is fairly common on these. However, tacking the bands won't really do anything as they are not going to be what is rotating. The turnout pipe from the manifolds slips into the front of the muffler and the clamp goes on the outside of the muffler to squeeze down on it. You would need to tack between the muffler and the pipe itself if you want to prevent rotation of the system.
Also, the tips can rotate on the muffler as well as they are clamped on the same way. Do you have 100% stock exhaust or something aftermarket? The stock exhaust on my 04 at least had a button on the pipe coming out of the cat that went into a slot that was cut on the front of the muffler. It was a very loose fit to allow for some rotation for initial alignment, but it would prevent some amount of rotation depending on how they line up. Aftermarket might be all smooth tube though, so more prone to rotating.