Flying high....Sideways?

[GreyGoose]

I noticed for a few weeks now that when goose flies to me he flies kinda sideways like a weight is on one of his wings,its not a great amount but noticeable. He also used to be able to fly longer distances and when he flies to me(about 7ft) he barely makes it and he use to go past me. Hes never had his wings clipped because she told me they didn't need it when I took him he also doesnt have any lift when he flies so I was too concerned about them right now, I was wondering if anyone has had it happen and if it will go away, or if it might have something to do with a lost blood feather but the last feather he lost was a month ago.