[CentOS] odd arpwatch error

On and off, I'm seeing
Mar 22 14:10:04 <server> arpwatch: short (want 42)

The only thing like it I find in googling is an old debian bug, with the
only solution I see, from
<http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=155182>, is "It seems
that "struct ether_header" was 2 bytes too long, and with attribute packed
it works fine on my NSLU2."

Anyone know if this could have crept in? Johnny? Karanbir?

       mark