Kiwi's leaves going white

I bought this kiwi a few weeks ago. It's been planted in a large pot on a south facing wall and was doing really well, but noticed that some of the lower leaves are completely bleached. Is this just the cold weather??

(The white on the leave isn't glare from the camera - they really are that white!)

It's in new general purpose compost - been in there for a couple of weeks. Haven't added any extra feed yet.  Any ideas gratefully received