Have you got it in semi-shade, out of the wind, in ericaceous compost and are you keeping it watered? Any of these factors will cause leaf drop.

One of mine lost most of its leaves in the fierce winds we had earlier this year. It used to be sheltered by another shrub, but that died last winter, so that was the reason. It's not dead, so I'm hoping for new leaves in the spring.

Most likely you damaged the water seeking roots when moving it - just keep it well watered till the plant recovers. If the leaves are not meant to be red all season, its likely it suffered a bit of drought before, and what you're seeing is early autumning due to that.