Cassio,
also consider that you may have a different variety of M. strigipes, and the color of the new growth may be variable between specimens, not only due to environmental discrepancies, but also slight genetic variations.
This is one of my favorite aspects about collecting Myrciaria/Plinia...an individual species can seem like 10 separate species, due to genetic variation....(something like Dogs...poodles, pitbulls, pugs, wolves...they're all same species....the amount of variation is astounding!)