I think that's the first time I've seen that reported. Are you sure that is what is happening?
In my experience the citrus aroma and flavor comes from the Coriander, and it's very easy to overdo. The amounts indicated in many recipes seem to be referring to really old coriander. I've only gotten a subtle background contribution from the peel both fresh and dried. I believe also the pith contributes some of the bitterness without the use of hops. Maybe I've always used fresh Coriander, but it's hard for me to believe that you need to add more or that would improve the balance.
Details on recipe?