What makes you think that it is, guest? You haven't told us the symptoms, so it's difficult to answer your question. If it's just falling leaves, it could be the effect of drought which seems to be causing premature leaf drop on some of my plants, too.

Please post your question again, and if you could add a photo and some details, that would help us.

And autumn's a coming - this is a deciduous plant, and we've already had some much cooler nights even in London.