'live on entry to lambda' warning

I'm seeing the following warning while compiling some
code with LW 4.4.6 on WinXP SP2:

;;;*** Warning in GRAPHIC-FORMS.UITOOLKIT.GRAPHICS::DATA->FONT:
(G329/NIL) are live on entry to lambda

DATA->FONT is a function in my code being compiled with the following
settings:

;;; Compiling file
c:\projects\public\graphic-forms\src\uitoolkit\graphics\font-data.lisp
....
;;; Safety = 3, Speed = 1, Space = 1, Float = 1, Interruptible = 0
;;; Compilation speed = 1, Debug = 2, Fixnum safety = 3
;;; Source level debugging is on
;;; Source file recording is  on
;;; Cross referencing is on

What does this warning mean and/or what should I start
looking for as the culprit?

Thanks in advance.

-- 
Jack Unrue