We've had our youngster for nearly 4 months, and this week I stroked the top of his head for about a minute for the first time ever. He flinches easily, and I haven't even tried to have my hand in front of his face, but when approached from behind, i.e. not seeing my hand, he's OK with having the top of his head touched.

Interesting about rubbing their chins. I'll try to work up to that.