Well I suppose that this is that 'grey area'. If the dominant partner comes home late for whatever reason he/she doesn't realy see this as wrong (in this case....atleast). They most likely see it as just getting home late. They are the dominant they don't have any 'rules' regarding that.
That is just my opinion.
*shrugs*
Had to add this. If it is or becomes an issue, bring it up.