So I have a vivace 4.2 stroke and my partner has a vivace 3.5. Mine has the purple /pink spring his has standard silver. When I use his vivace I notice a bit of heat, nothing serious just warm. When he uses his he runs a bit less voltage and is not that noticeable. But with the 4.2 and pink spring I get lots of heat. No sound or performance downgrade. No burning smell, and not so hot I can't hold. But damn it's pretty hot. Had my partner use it as he doesn't heat his and he was surprised at the heat. Any known issues wwith heat and not a bad motor? Is this normal?