Hmmm...have you ever wondered if it just some thinly veiled excuse to engage in some conversation with an attractive woman with that being the most immediately notable thing they can think of. You do have to admit that men are men and you can't put it past us.
Also, a heads up about grocery stores like above, if some guy just happens to gently bump into your cart with his own there is a reasonable chance it's not an "accident". I've never tried to pull off the maneuver myself to start a conversation with a women, but I have seen it attempted. :1orglaugh