The doctor basically said that his head circumference can't be measured the same way as a full-term baby and since it is increasing in proportion to his weight, he didn't find it concerning.
They also included another little paragraph which said:
JoonSeo is now crawling on his knees and then can move on his own into a sitting position. He sits and plays well with his toys. He holds on and stands up and then moves to the side (cruises). If his birth at 30 weeks is considered, his developmental status is steadily improving. We look forward to JoonSeo growing well with a healthy appearance and hope that he will be able to be in the embrace of his adoptive parents soon.
:-) :-) :-)