Coolant leaking from radiator cap

dohblah

I have a 2005 Dodge Grand Caravan. I recently replaced the radiator on it and then found that when the engine heats up I start losing coolant from the radiator cap. I thought maybe the cap was bad, so I bought another one and still see it spraying once the engine heats up. I took the rubber gasket off the old cap and added it to the new one (double gasketing the new cap) yesterday and that stopped the leak. However when I got up this morning and the engine is completely cold I went to check the radiator levels and found that the upper radiator hose was still a little tight and when I opened the cap a little fluid and air sprayed out (it was still under pressure).

So could the double gasket be blocking something to the coolant reserve tank? I pulled the hose off of it to make sure it wasn't blocked and it flows fine from the reserve tank.

Any advice?