brake booster prob

[76bonanza]

I have a fairly new booster maybe 4 months no issues ever. Today cold and wet. On way home first brake push full power great if I imediately push again less and so on. If I let it up for a few seconds good again. get home pull hose fool with it check valve and gromet all good hook back up. Seems the same then stops, and is all good, drive around a few minutes good as gold? Any thoughts on this or this happen to anyone else? could somthing have frozen up? The brakes always worked just less power assist like it was not getting enuf vac.