two tones of color on leaves

planted some belladonna seeds and its about 2 months old
now and the bigger shade leaves have 2 very distinct colors
. the center of leave is dark green and the outside edges
about a 1/4 inch stripe of almost a greenish yellow the length
of the leave ,and the smaller ones also are starting to show the same traits.
anyone haveing any good knolage of the belladonna strain plz get back to me on this." is common in the belladonna strain???.
my camera shit the bed so I cant provide a pick of the plant..