I agree too that a few, in terms of days, is 3 or 4. I can't see why it would be an absolute number, e.g. 3, as one poster has said, because why on earth would the term have come about? That is manifestly absurd. A few, several, some, a goodly number, quite a number, quite a few... they're all ways of describing an unknown quantity.
Someone told me many years ago that originally a 'moment' was one and a half minutes, and not the unspecified period of time it implies today.
I've only just remembered this and googled it. I came up with this fascinating wiki article