Sometimes when you flip your phone around too quickly, it won't register vertically. I'd say just double check you're in the correct position because that was probably the case.
If the thing you describe is what I'm thinking of (they show sideways in the gallery), my M8 would do that and I'd have to choose "rotate" in the editor.
If the thing you describe is what I'm thinking of (they show sideways in the gallery), my M8 would do that and I'd have to choose "rotate" in the editor.