origin defaulting to undesired domzin in zone file transfer to slave

Origin should be operon.com
As you can see '@' was employed in the SOA record on the master side. I
understand that means the domain name is based on the second field of
the zone statement
in named.conf. However in our zone file there are three zones and on
the slave,it appears to have defaulted to operon.net as opposed to
operon.com. BTW, The master
seems to function fine with this setup. I suspect substituting
operon.com in the master's zone file will do the trick but, I'm curious
about the mechanism and if there
is an alternative solution.

master's db.operon file

$TTL 86400 ; 1 day
@ IN SOA kenny.operon.com. hostmaster.operon.com. (
2003080901 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS ns1-auth.sprintlink.net.
NS ns2-auth.sprintlink.net.
NS ns3-auth.sprintlink.net.
MX 10 wendy
MX 20 kenny
MX 30 cartman

......

here's named.conf from the master

zone "operon.com" in {
type master;
file "db.operon";
notify yes;
allow-transfer {
####
};
};

zone "operon.net" in {
type master;
file "db.operon";
notify yes;
allow-transfer {
####
};
};

zone "qiagenoperon.com" in {
type master;
file "db.operon";
notify yes;
allow-transfer {
####
};
};


.......

here's named.conf on the slave

};

zone "operon.com" in {
type slave;
file "bak.operon";
masters { #### };
};

zone "operon.net" in {
type slave;
file "bak.operon";
masters { #### };
};

zone "qiagenoperon.com" in {
type slave;
file "bak.operon";
masters { #### };
};
.......


version ends up on slave after transfer.

$ORIGIN .
$TTL 86400 ; 1 day
operon.net IN SOA kenny.operon.com. hostmaster.operon.com. (
2003080901 ; serial
10800 ; refresh (3 hours)
3600 ; retry (1 hour)
604800 ; expire (1 week)
86400 ; minimum (1 day)
)
NS ns1-auth.sprintlink.net.
NS ns2-auth.sprintlink.net.
NS ns3-auth.sprintlink.net.
A 198.68.215.35
MX 10 wendy.operon.net.
MX 20 kenny.operon.net.
MX 30 cartman.operon.net.
$ORIGIN operon.net.

.......

--
Thank You