If an employer has given you your next weeks schedule and then revises it while you are not there, aren't they required to call?

I have a small pt job w Ross Stores.........when I left last Thusday, I wrote down my shift which ws for today and tomorrow from 11:45 -4:15 -- I got up this morning , showerd , etc, put on my little black pants and royal blue shirt uniform and went to work..........i went into the back room and saw a "revised written on this weeks schedule" so I ckd it thinking perhaps they gave me morehours..........nope.......instead, they had removed me from todays schedule and no manager or asst bothered to call me to let me know................that does not seem right to me.............I felt like just clocking in and sitting there.............is there some kind of labor law that if you are removed from the schedule, that the employer has to let you know......? just not not seem right tome.........