I'll third the motion on this also. Same thing with mine. I have it away in storage, but start it once a month and let it run for about 15 minutes to get it up to temps. Mine will spray some water out too. It's condensation sitting inside the muffler and pipes. bad thing about it is that's what rots your exhaust!
I know what I'm doing is kinda useless, starting it and all, but I do it to keep the engine and gaskets nice and lubed and the fuel line clean. Besides, next spring I'm putting in new mufflers and tips so what the h#!! right.