Facetime option does not appear for one contact.

I have the following issue: I added a new contact yesterday. She is an iPhone user as well, but for some reason the Facetime option did not appear in her contact card. The weird thing is that this is the only contact with such a problem. If I add another iPhone contact the option is there. So the problem is only associated to this specific contact. I deleted it, added it again, tried a force restart , to reset the network settings but the problem insists. Furthermore if someone else adds her as a contact, the FaceTime option appears normally.Any ideas? Anyone else experiencing such a problem ?