Unusual? I really don't think so....often they're very well balanced and at times clumsy. For the most part mine are athletic and well balanced, but every once in while one of them will misjudge how high or how far to jump. I think most of us, animals included have awkward days. I would only be worried if this was becoming more common than occasional, as it may be beginning of some sort of problem.....increasing weight?....arthritis?....an injury?