A slight amount of rotational movement of the lens in the adapter is normal and nothing to be concerned about. All lenses rotate a slight amount in any mount (be it brand name or third party) this is due to the space needed for the locking pin to engage, so that slight rotational movement is the locking pin moving around in the hole.

If there is ever any more than a slight amount of rotational play, you may want to try tightening the lens mount adapter so it will hold the lens tighter to the mount. There are 3 flanges in the middle of the adapter (what the lens locks onto) that are split open slightly, this gap is what gives the tension that holds the lens tight to the body. Over time and with use these gaps decrease in size, no longer pulling the lens tight to the adapter, which allows the lens to move inside the mount more than it should.

To tighten the fit, get a slim metal object (a #1.5 or #2.0 small flat eyeglass screwdriver is ideal) and insert it into the slit to open it up just a little bit (see images below, make sure to do it to all 3 evenly). The more you open the gap, the tighter the lens will be to the adapter; too much and the lens will have a hard time mounting so make sure to do it just a little bit at a time to all 3 flanges evenly, it doesn’t take much at all to get a tight fit.