Some airlines ask to see the credit card used to pay the ticket or they won't let her board. Better to inquire about it; if this is the case, usually you can circunvent it going to a bricks and mortar point-of-sale for the airline, present the card there and ask for it to be annotated in the PNR.
Or just book through Orbitz, Priceline, Yahoo Travel, etc. If you booked through a third party, airlines never ask for the credit card.
But to answer OP's question, this is not a problem and people do it all the time.