Should I have a feeling obligated?
Answers: Sounds easy plenty. When your job is paying you ample that they've earned the right to suggest that your existence and your needs come second to their agenda, that will be when you can pick up more time. Until after, Who gives a flying flip in the region of their issues. Think about it ... what are you going to do,miss your doctors appt. and bring your kid(s) to work beside you? Breathe
If you really have something to do and merely can't make it, no. They hired you segment time. They didn't require it of you to pick up for people's hours.