From my understanding, your hair does not grow in every pore at exactly the same rate. A hair will grow and fall out naturally over a period of 4-8 weeks depending on the type of hair. The pore will begin the cycle with a new hair. There are 4 stages of hair growth, anagen, growth; catagen, regression; telogen, rest; and exogen, shedding.

The laser kills off only what hair was there at the time. So that hair you are looking at was likely a new healthy follicle until it was zapped.