Mail can take up to 10 days to get from one place to another. I send out templates to people all the time. I had a check sent to me from an hour away from where I live. It took 3 weeks for me to get it. It had been remarked by someone in the postal system and had gone to two other states twice before some kind soul at the po saw it and sent it my way.
Generally speaking most things take about 4 to 5 days to get from one place to another here in the states but that can be more if there is a weekend or a holiday or if you mailed it after the pickup time for that day. Our mail is picked up at 4:30 promptly so if I take it in at 4:20 it won't go out as they have to have time to process it first.
And that is providing it didn't get stuck in the sorting machine or get ripped and kicked out into hand sort.
A week is not very long to give her before you get too concerned. I would allow at least 10 days and then if it didn't show up I would contact her and try to track it.