Keep it! The black label long suits run very short. If in fact someone really needed a long, I suspect they wouldn't purchase anything black label as it won't fit properly. If it is measuring 31" from the bottom of collar than it is 32.5" overall which is exactly what a regular should be.
That was my feeling too. I guess I'm more trying to decide whether I really need a basically solid brown suit. I kind of like it, but I wonder how much I'll wear it.