Over the years I've made many a mistake with my GL1100 stdaspenstate, in the 12 years I've been learning about it, one of the biggest ones was turning off the gas at the petcock for more than a month or so, especially in the winter time. But that does not make me immune to advise!
For years I would shut everything down for the the winter and this obviously included shutting off the gas, this manifested itself as a really bad leak from the carbs all over the engine, the minute I turned it all on again.
So my Advise is this, don't let those carbs dry out, all those O rings and such need to be wet with gas, all the time.
I never had the problem since I stopped turning off the gas!!