Portlet API jar

Can anyone shed some light on why the portlet-api-1.0.jar file that 
comes with pluto is different than the portlet.jar file found in the 
final release zip that I downloaded from the jsr-168 site. I stumbled on 
this when I was doing some debugging within Eclipse and tried to attach 
the source code to the jar so that I could set some break points in 
GenericPortlet. The line numbers didn't match with the source. So I did 
a little more checking. The size of the jars are different by 1k. So 
then I ran a checksum on the two jar files and those were not equal 
either. To take it one step further, I unzipped both jars and ran a 
checksum on each class (using a script of course). The classes the 
reflected a difference were the following...
    GenericPortlet
    PortletMode
    PortletSessionUtil
    WindowState
    All Exception classes

Can anyone from the pluto team help explain? Was the api jar recompiled 
at any time?

Thanks
shmoe