At first, Patty noticed Anton because he spoke very clean English, and he did not sound German at all. He spoke like an Englishman.
But she continued to watch him because he did not remain with the group. He left the group to wander the store and look at items, while they all stayed near the straw hats and asked for a mirror in which to view themselves. She continues to watch him, at one point even hoping that as he walked toward the door, he'd make the escape for freedom.
"I closed my eyes and prayed that he would make it all the way to freedom."
Patty was attracted to him because he represented herself. HE was trapped, bound by the fact that he was a captured Nazi. But his easy going manner and the way in which he spoke with her made him seem like a good man, a free man. This is representational of Patty herself, who feels trapped by her family's life, but feels free only deep within herself.