It isn't an excuse, as I experienced it last month with my 7th gen Exi, though I got only one bushing replaced, the rear right one. The car seemed higher from that end and sagged a bit lesser as well, I mean I could feel the other side riding a bit 'lower' than the other.
I inquired the very same from the guy who installed the bushing, he said the rubber will set in after a few hundred kilometers and the issue will go away, since currently your new bushing is slightly MORE rigid than the older one.
I did go away, by itself.
However if you fear he might have messed stuff up in there, its usually suggested to observe any differences in the drive and weird sounds/noise from the area of the suspension under focus. Unless it is so, I don't think you should feel any unnecessary urge to get wrenches turned yet again.