Hi,
That's more or less the things I have read: mobile phones are to blame, consequent shortage, manufacturers can't keep up with demand. Not sure about the bit about the other sizes. Worrying is one source I read claiming resistors will be next for some questionable reason or other.
True or not, unfortunately that is unprovable from where we're sitting and due to the access we have to incontrovertibly factual information we have.
I'll guess that a part of the problem is some of the more informed have stockpiled well in advance.