Not necessarily. I would argue that any reasonable intelligent and competent employer/supervisor would recognize that an unhappy employee is going to provide diminishing returns over time, and the employer would be better served helping them explore related opportunities in the company. I've seen programs to help employees do exactly this at every place I've worked.

The only cases where I think it would usually be a problem are if your end goal is not with the company, or if the end result is seen as a going down the ladder (example: QA personnel moving into development is a positive move, but developers becoming a tester is often seen as a negative move)