In my experience, she should be okay, but she'll have to move quickly.
International arrivals will be @ Terminal 5. She'll have to clear the immigrations hall, get her baggage (if she has any), go through customs, drop off her luggage (if she has any) for domestic routing, take the tram over to Terminal 3, go through TSA security, then head to her gate.
The last time I did this, I had a 2 hour layover and had about 15 min to spare.