You would need to confirm it with Pepperstone, but the new CFTC regs would be the most likely explanation.
The CFTC is suing unregistered brokers with offices in the US - a good thing. The CFTC is also suing more and more brokers that solicit business in the USA - a not so good thing, since it looks more and more like "accepting US Clients" equals "soliciting business in the USA" in the eyes of the CFTC.
From what I can tell, the excuse of "protecting US residents from fraud" is being used to make it harder and harder for US residents to have any sort of financial dealings overseas, even with well regulated institutions in Europe.