This is actually questionable. Sam was in the womb at the time of this leap, something according to my behind the scenes book that actually happens a few more times. It could be several errors in choosing leap dates or QL could be pro life, considering existence in the womb to count as part of one's lifetime.
Actually (and I'm not sure if this was intentional or coincidence) with the exception of The Leap Back and The Leap Between the States - for which we are given other specific reasons why Sam leaped outside of his own lifetime - none of the leaps that took place before Sam's actual date of birth took place earlier than April 1953. Which is when he would have inarguably (and legally) been considered viable - so, yes, part of his lifetime.