Possibly.
The majority of the time I see it is the opposite, when a dog is first getting started and is totally geeked-up.
Totally disagree.
I don't think the dog has any conscious control of it at all, it is something they "just do" ...
I am an old timer now, and I have seen (and bred) more absolutely, truly game dogs than that old timer (and you) put together at this point ... and NONE of the dogs in question ever quit ... it was just something they did in the beginning, when they were amped and pumped.
And, again, my house dog does it when I feed her ... or when I grab a toy ... ANYtime she is excited.
For anyone to conclude that she is "about to quit" because of this sign is basically a moron IMO.
Like I said, she is basically saying, "It's on!"
MEAUXTIVATION's experiences echo my own.
You may have different experiences, and seen different things in different dogs, and so I can understand having a different view ... but I know what I am looking at in my own dogs, and don't for one second to presume otherwise.
As a matter of fact, that old timer is the one who wound up counting 10 over his own dog ... after he finished telling me "all he knew" about the signs in my dog
Jack