In all honesty, you made a mistake accepting delivery. Until you accept delivery, you don't need a reason to say no, afterward you do. IMHO I think this is sub par and trek should replace it, even if it's only cosmetic.

For future reference to other readers of this thread, if you're delivered a bike that you don't feel comfortable with, don't accept staff reassurance that it's OK and walk out the door. It's better to leave it with them as undelivered while you think about it. Afterward with no pressure you can decide if it's OK, ie cosmetic and minor, or if you really want a replacement or refund.