Should data directories match between master and hot standby?

Hi all,

I have a hot standby (via streaming replication) set up on a postgresql
9.0.4 system.

(I'm looking at base to eliminate differences in xlog and pg_log, etc)
The size of my base directory on the master is 775G, the size of the
base directory on the hot standby is 804G.

Is this normal? Collecting the info from the master and the slave using
the following shows I'm in sync:

[on the master]  select pg_current_xlog_location()   ->
pg_xlogfile_name_offset -> (0000000100007AB0000000E7,7282688)
[on the slave]  select pg_last_xlog_receive_location() ->
pg_xlogfile_name_offset -> (0000000100007AB0000000E7,7282688)
[on the slave]  select pg_last_xlog_replay_location() ->
pg_xlogfile_name_offset -> (0000000100007AB0000000E7,7281296)

So I'm in sync, not like the slave is waiting on a huge delete or anything.

Any thoughts or ideas what this could be?

Thanks in advance,

- Brian F