Please Help! Purple under leafs!

I just started growing some Nirvana Bubblelicious. They are only about 1 week old and they are turning dark purple under the leafs but not on the top. Is this normal?DSCI0923.jpgDSCI0928.jpgDSCI0925.jpgDSCI0924.jpgDSCI0929.jpgDSCI0927.jpgDSCI0930.jpgDSCI0922.jpg
 
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