No they are not new. I have had them for 7 months and the guy at my Lfs acclimatized them over the coarse of a year to live in water with a pH 7.2-7.6. That could be the reason perhaps. Also the water is tannin loaded which could be a factor. They eat like pigs though.
Very nice! Great looking altums you have there. I was gonna say that the tannins tend to make these fish look like they are not showing there bars, but there bars are almost the same color as the tannins.