Are those pictures of him moving accurate depictions? I'd be interested in seeing more, or video. Does he trot straight forward, or is he angled with respect to his direction? I don't think he's in danger of a leg falling off or anything, but what I see is a significant imbalance between the angulation of the rear and the angulation in the front. I agree that he has too much in the rear, but I think there's something else off that I can't place my finger on.
You can see in the first gaiting shot how he's fully extended his left front leg, but there's still a lot of bend in his left rear. His back legs are writing checks the front can't cash.
He also looks pretty close to square, which means the space under his body for his feet to go is at a premium. With long legs with a lot of angulation, that might explain why his right legs look awkward to me.
Is he significantly more muscled in the front or the rear? He's young enough it might not have had time to build up, but if say the shoulder muscles are significalty more developed than the rear, you know the rear is weak and the front has been compensating. I went to a Pat Hastings seminar where she pointed it out on a boxer-type dog, and it was really easy to see.