There is a wet spot in my yard, should I worry?

Yes.  Sewage leaking to the ground is a sign of a problem with your drainfield.  Letting the leak continue, without repair, is harmful to any pets or children who play in that area.  It is basically raw sewage that is no longer leaching into the drainfield as it is supposed to.  It will go to the point of least resistance, and that is often the yard.  Allowing children or pets to play in the yard is exposing them to diseases carried in the sewage.