The minions pictured on the very same page are clearly a darker shade of yellow. When I grap the pantone color with a color picker I get #f8e763, while a minion gives me #fad24e.
That could be from a number of different effects, ranging from render parameters (of either the minions, the color sample or both) to optical ilussions. Also, they may already have a similar colour and chose to name "minion yellow" a new shade, which still resembles the minion's iconic colour.