So when I was grouse hunting with Rowdy today and quail hunting the other day I noticed that when I blow two pips on the whistle as his recall command he stops right where he is.  It's obvious the whistle catches his attention and he stops.  The thing is, that prior to these past two times, he comes running back to me the first time I blow the whistle, I'd say about 90% of the time.  He definitely knows what the command means, but being a puppy it's still not a sure thing that he'll come the first time.  This new behavior of simply stopping when he hears it has me perplexed though.  He'll come the second time I blow the whistle after he stops, but I don't want to teach him that he can ignore it once  and then come the second time.  Should I just go find/get him after I blow it the first time, so I don't have to blow it a second time?  Or since he's a puppy should I just do nothing after he stops and let him eventually come back to me?  Any suggestions on how to help him understand that he has to come the first time are welcome.  I realize he's a puppy still, but I would still like for him to come the first time, if possible.  Thanks.