Unless your phone is in card emulation mode, the card-polling example would normally not detect the phone as a card. That is, before Android 4.4 (and on NXP PN544-based devices) card emulation is normally not enabled. Though the polling example looks as if it could potentially detect a phone's passive peer-to-peer mode (when display is on and device is unlocked) as either "Mifare" ISO 14443-3 or "FeliCa" due to the fact that those modulation and protocol activation schemes are used in peer-to-peer mode too.
For reliable communication with an Android device, I would suggest that you use either the peer-to-peer mode (P2P) example or the card emulation example.