I wouldnt worry about it sometimes purpling comes from a dip in temperatures possibly when the lights are off.Is purple coloring on the underside of the leaves bad for a 10 day old indica dominant?
heres a pic, the strain is ganesh from mandala seeds
lights are on a 24hr schedule, and temps are usually 75-80F. i am beginning to think its just genetics. my other ganesh has purpling also, just not as vibrant as the one in the picture.