why not speak up? something simple like "I feel like youre always kinda rude every time I come here" they'll be shooooooook

Or the next time, you could just ask them how their day is. If they still seem cranky, you could mention that they always seem unhappy when you come in. Kind of a, "kill em with kindness," approach.
Or if they are just a butthead to be a butthead, like Linda said, it may really f#@k with them.