We complete our education start a job and then tend to stay in that job for too long. This is the tendency of most human beings as we are basically creatures of habit.
However, if it has reached a point where your job does not hold any challenge or give you the opportunity to learn and grow then you should step back and seriously review the situation. Staying in a job that requires nothing from you intellectually or creatively is the biggest disservice you may be doing to yourself.
Some signs which you may watch for are :