[racket] unsyntax in Scribble examples

Compiling the following Scribble program complains that x is unbound
on the last line:

#lang scribble/doc

@(require scribble/eval)

@examples[#:eval (make-base-eval)
          (define x #'q)
          #`(a #,x c)]

Of course, it is unbound in the expression doing the eval-ing, but
that shouldn't matter because it's only the eval-ed expression that
refers to x.

Is `examples' doing something, or am I?