1996 auto trans pushing fluid out dipstick

I have 1996 gmc 4.3 with auto trans and it has started pushing fluid out of the dipstick. It is getting progressively worse.I have never changed the fluid in 93k .So I guess I will start there. Any ideas.Also I have noticed that if I have the motor running and I try to ck the fluid ,the longer it sits there the higher the reading is.Like the fluid is building up in the tube . Help

I solved the problem,It was a plugged filter in the auto trans,Whew!