I have one of those frogskin acros (A. tortuosa I think), and it has colored up nicely under my MH's. Starting to turn a very pretty light blue with teal polyps. Mine started out just the way yours looks and it took about 2 weeks to really start bluing up.
Good to know Epos! I'm putting in new T5 bulbs in the frag tank this week, gonna try a fiji purple, ATI aqua blue, and an 11k Giesemann. Hopefully that'll brighten everything up a bit.