Ive had purple stems from bagseed before its nothing uncommon. if its a purple strain
ex.purple kush then you should know because your buds you had and likely smoked by now would have purple leafy/ resin gland parts. By the sounds of it if your early in the grow you wont have signs or even traces of colour. Atleast not now. If you have the capabilities to post pictures that can help out as well as when we can tell if its a indica,sativa or cross it can aid in identification as strains can be eliminated.
I hope this helps you out.