You probably don't need this answer anymore, but for other folks following, sample cans come with a different base paint than whatever product you eventually chose for the gallon. The base colors in the can before you add pigment affects the outcome of the color, especially with whites and lighter tones. SW is notorious for having grayish base colors...like all their white-whites actually seem a tad gray. BM is the opposite, even their warm grays seem like they pop cool.