During the early season our dogs would also occasionally retrieve turtles, especially when bird encounters were scarce and the dogs got bored. An old trainer told us that it was about the similarity of scent. Not sure how he knew how turtles smelled

but there may be something to this. Snakes also get pointed (never had a snake retrieve, but snakes are not as "nugget like" as a turtle). There is speculation that birds and reptiles have some common ancestry (hey, don't we all?), and that the scales on birds, turtles and snakes is an indicator.
Part of the mysticism of being owned by dogs I guess. So, maybe it's just Griffons and Gordons...who knows.
I just want a Gordon to retrieve a woodcock from across a stream like yours do, Chris.