Sounds very much like your grey is regurgitating,A parrot regurgitates usually for one of two reasons, he is ill or he has decided you are his mate & he is showing you affection.The drooping wings along with whimpering noises is also accompanied by a bobbing or pumping movement of the neck.If this is the case it's best just to ignore this behaviour,walk away for a few minutes.
However, just to complicate things, a sick bird also can make the bobbing movement,if this is the case keep an eye out for food in the cage that has been vomited, changes in droopings,perching fluffed up etc..