big bad billy

i have a 95wrx saloon, when i drive it the suspension seems to be o.k, takeing bad road surfaces and potholes without any nasty knocks or bangs,but when the car is at rest for awhile,i give the rear dampers aheavy push test it feels really soft and weak.but as i continue to push it stiffin's up!! do's this mean they are on their way out?
any comment will be appreicated.