Top Radiator Hose

Hey can anyone answer this for me? I just put a new water pump in Pearl (1966 Plymouth valiant 225). She was leaking lots of anitfreeze but now no leaks. I also put a new gasket in the thermostat housing because, you guessed it, it was leaking. Took her on a drive today about 63 miles. Ran perfectly, temp was great, however when I got home and opened the hood i noticed the top radiator hose looked like a balloon. I let the pressure off lifting the stem on the radiator cap and the hose went down. Best thing is still no Leaks!!!!!!!
Any ideas about the hose would be greatly appreciated.
Thank you,
Mopar Pearl