I would try changing the transmission fluid and filter in the pan.  This may
help.  However, my transmission does this as well (although not very badly).
If the filter doesn't help then it is just a worn ATF pump and the thing
needs a rebuild.  However mine does this when stone cold in the morning and
the rest of the day shifts great.  I ignore it and feel that this problem can
be ignored (unless you are really anal) until you get to the point where the
transmission is shifting terrible going down the road (mine shifts great!).
I have new Auto Tranny Filter Kits for $10 on my website (see url below).

Hope this helps,
Ken Wilford
http://www.vanagain.com
John 3:16
Office (856)-765-1583
Shop (856)-327-0027
Fax   (856)-327-2242