Thats not really odd.. there could be many reasons.. maybe her mom has soemthing going on medically and needs help around the house, or maybe she jsut wants to go see her mom and he can't get that type of time off from work, lol
I know that all my family lives in NJ and only my mom lives here.. Being so far from everyone, it sucks to only be able to see them a week here or a weekend every 2 years.. after my grandmothers passed it really opened my eyes to how bad it sucks to live far from your family, cuase I would do anything to go back and spend another hour even with my grandmother.. now I take every opportunity I can to spend as much time as possible with what family is still around..
I am sure you will find ish to occupy your time.. time will fly by and she will be back before you know it, lol