export-syntaxes requires a syntax class for transformer expr?

[quasarbright]

(syntax-spec
  (nonterminal/exporting anim-expr
    #:allow-extension racket-macro
    ((~literal define-syntaxes) (x:racket-macro ...) e:racket-expr)
    #:binding (export-syntaxes x ... e)))

gives the error

export-syntaxes: expected pattern variable associated with a syntax class
  at: e
  in: (export-syntaxes x ... e)

examples seem to use e:expr instead of e:racket-expr. why? seems like we should be able to use racket-expr