Glider

That's really odd. Looking closely, those leaves don't have the dull, flaccid look of 'sickness' that would suggest a major systemic problem (e.g. root rot or some other sap interrupting problem that would make the whole tree sick). Apart from the curl, they all look quite glossy and turgid and are a good colour. The leaf axils are all turgid too, all holding the leaves up well and not curling down.

The only times I have seen leaves curl like that are when the undersides are either infected with powdery mildew (it's a bit early for that yet) or under severe insect attack (loaded with aphid). I can't see any overt signs of either.

The tree looks like it's still pushing out new growth too, so again, there doesn't appear to be any systemic problem with the tree.

There doesn't seem to be any sign of 'sickness' or infection, so if it were mine, I would put it in a sheltered spot with good light and wait a little while to see what the next set of leaves do.

The first set may have curled simply due to some anomaly in the conditions when they were opening, e.g. a particularly cold night or two, a temporary drying out due to some particularly drying winds (we've been having problems with that recently, high winds but very low relative humidity which can dry out tender new growth very quickly), or a bit too much sun? (I don't know how strong the sun is there in March). Was it repotted this year?

In any event, it's impossible to treat the tree for anything in particular until that thing is identified (which somebody else might be able to do), so until then, a good dose of TLC and close observation would be in order and might well be all that's needed.

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