AusBonsai

I bought an old Banksia Integrifolia bonsai a few months ago. It was positioned under green shade cloth. I have all my bonsai in full sun, which is where I left it. Living in Western Sydney we have had some frost over the last few weeks, but last Wednesday was -5 at my house. Half of the plants leaves have gone white.

My question is has anyone had this happen before?
Is it frost damage?
Could it be from going from under shade cloth to full exposure to the elements, and a particular cold morning for this area?

Thanks,
Matt

We regularly get -5C down here and Banksia integrifolia seem untroubled even with open to the bare sky so my guess is some other issue has caused the leaf change.
Change of sun exposure could do this though the sun should not be that strong this time of year.

Are there black spots on the under-side of the leaves? If so, check out this discussion thread on them. viewtopic.php?f=69&t=30827