There may have been damage to the crown of the plant from frost. It should work itself out as the year progresses.

Dicksonia needs plenty of water, especially if newly planted, but as usual with plants like this, it is easy to overdo it too. In drought spells, apply 2 or 3 litres of water twice a week. The fronds will droop quickly if it is in trouble.
Don't feed it too much nitrogen as it will not survive the winter if too soft. Tomato feed if you think it needs it.