messageExchange.requestContent does not return valid xml in Soap3.0

On a Script Assertion written using SoapUI 2.5 ,  the method call messageExchange.requestContent returned valid xml - and thus could be passed as a parameter into groovyUtils :

    groovyUtils.getXmlHolder( messageExchange.requestContent )

When running the same Script Assertion after installing SoapUI 3.0, messageExchange.requestContent now reuturns the pre/post-amble to the xml content as well:

Tue Jul 28 15:09:47 EST 2009:INFO:messageExchange.requestContent
------=_Part_73_19105844.1248757714698
Content-Type: text/xml; charset=UTF-8
Content-Transfer-Encoding: 8bit
Content-ID:



------=_Part_73_19105844.1248757714698--

and therefore groovyUtils.getXmlHolder( messageExchange.requestContent )
fails ( returns null ).

Is anyone knowing why this would happen ? Is there a fix/workaround ?