For me it was kind of a burning feeling, like rug burn. It can be your shaft stretching too.
What wight are you starting with? How many sets? And how far back are you setting the hanger?
For me they can get cold fairly quick and even turn very blue with heavier weights. 20 mins is the suggested time for a set because it’s a clamp style hanger and the thinking is after about 20 mins the cells start to die from lack of oxygen. Right now I’m 12 mins into my first set at 7.5 pounds and it isn’t too cold or blue yet. The other day when I put 10 pounds on it went cold and blue fast I assume it’s a mix of my wrap and getting used to a new weight. I haven’t hung 10pounds since last year before I stopped hanging. Hanging is a trail and error form of PE. You’ll get it figured out. Read and watch as many videos on it as possible. Good luck