Fixed with:

commit f6065cb30e016a76a450ce8aefa91722624b0770
Author: Michael Prokop <mika@grml.org>
Date:   Sat Sep 4 12:27:21 2010 +0200

    Update isolinux.bin and vesamenu.c32 to 4.02 debian-20100803.
    
    Taken from syslinux-common 2:4.02+dfsg-3.

We decided to continue using the files shipped by grml-live and grml2usb uses 
the isolinux files from the syslinux package of the host (if present).

regards,
-mika-