Yes the problem is because of the new aviation laws about shipping lithium batteries. You can't ship them now in the hold of plane so they have to be in hand luggage and a lot of the mail companies have started additional security check to try to prevent them being sent.
Hong Kong Mail and Singapore Post have been particularly bad and I think their backlog is because they are x-raying every parcel.
I know this because I order lithium batteries from the far east for my ecigs and the main company I buy from has been keeping me up to date with what has been happening. They've started to ship batteries with their boxes wrapped in foil so they don't show up on x-rays
Absolutely bloody stupid rule which is going to have to be revised pretty quickly or no one in the West will have mobile phones pretty soon. Typical instance of decisions being made without considering the implications.