Am I a bad person for this?

My daughters are 2 and 1 and recently I started a new job. I was workong 1st shift 6am-3pm but it was hard on me so I switched to nights and love it its 7pm to 4 am and so that I can get some sleep I switched my daughter's schedule a little bit. My mom who watches while I work puts them to bed a little later so that they will sleep in so I can get some sleep. Does that make me a bad mom for fixing their schedule to fit mine? I have a few snobbish co workers (from day shift) saying its messed up but how???? Im doing what is best for me and them because night pays more!