I was working on my bike the other day and noticed that the Brooks B17 saddle was not level left-to-right. It's about 1-3mm higher on one side.
I pulled it off the seat post and sure enough, one of the rails is shaped slightly different from the other.
Now, I've had the saddle for almost a year, and I don't think my tush notices the slant, but I do recall a few months ago wondering why the bike pulled to one side when I took my hands off the bars. I attributed that to a nearly empty pannier on one side of the rear rack.
I know that Brooks saddles are known to morph to fit a tush, or perhaps it's the tush that morphs to fit the saddle, but is it possible the saddle rails where straight when purchased and have since bent?
As far as a break-in period... I remember that the first few hours on the brand new saddle where very uncomfortable, but just 15 miles into the saddle it didn't bother me anymore. I think it feels the same now as it did back then after the first day of use, just fine. So if Brooks will take the saddle back I don't think I would have a problem breaking a new one in.