I just purchased a 2005 Pilot EX.  Upon getting home and sitting in the
garage admiring the interior I heard the door locking mechanism engage
on all doors.  At first I figured it was some feature like GM has when
you shift from drive to park but it continued to happen randomly 4-5
times per minute.  I thought maybe the remote(s) were the problem and
took them to the other end of the house out of range.  That was not it.
I then noticed that this happens all the time, driving down the road,
stopped at a light, or in the garage with the keys at the other end of
the house.  The only way to stop it is to lock all doors.  If I lock
the doors with the remote or master lock it usually stays locked but
once in a while it will immediately unlock.  If I lock it and wait 5-10
seconds and it doesn't unlock then it seems to stay locked.  I have an
appointment to have the dealer look at it but it's not until the end of
next week.