I guess it depends if you mean it feels tight/uncomfortable or if it actually HURTS. Because tight/uncomfortable is normal (at first - after one or two washes it should be not that uncomfortable at all beyond sweating/some compression while bending over and whatnot). It it actually hurts, I'd advise you to move a size up, because it can cause some pretty painful injuries (talking from personal experience here - every couple months, even when I bind properly and safely, I get inflammation in my ribs because I've been binding for 4 years now).