I do not own any pastel boas, and do not know too much about them. However, from what I have seen on the net, your does share at least one characteristic of a pastel, which is the pink hue down its sides. Pretty boa either way. Yes, the boa will eventually darken. It surprises me sometimes how their colors change so drastically from baby to adult. My adult salmon male looks nothing like when I acquired him at a few months old.

Boas are really tough to take pics of. Once out of their cage, they are all over the place. The last pic is a good one. It shows off his colors nicely.