I very much doubt that any painter would give an implicit 5 year guarantee. Depending on the age of the woodwork, direction it's facing and humidity or dryness it's impossible to make that sort of statement. He probably told her that the manufacturer guarantees it for 5 years, Dulux do with their Weathershield paints, but I expect that she's giving you an abridged version to fit in with her narcissism. Smartest move seems to be going on Holiday for a couple of weeks !