I think that it is a fault if a rhododendron blooms in the fall.  Most fall blooming plants do it sporadically but one of my hybrids does it every year and it is such a waste because it is a good yellow.  It is  that I grew from seed from John Nicoletta.    I call it ‘Autumn Gold’ for the fun of it. The problem with fall blooming rhododendrons is that they partially only open two or three flowers.  That destroys the bud for next spring and thus no flowers appear from that bud in the spring.  Cunningham’s White is so famous for this trait that one way to identify it is if the plant puts out some white flowers in the fall it is Cunningham’s White.  One of Hardgrove’s hybids, ‘Golden Star’ has done it a couple of years.  Here is a picture of ‘Autumn Gold’ taken on October 7, 2016 taken with a flash as it was getting dark when I saw it: