Dhcp server sends lease time value which is bigger than configured.?

Hello,

I have setup with 3 nodes. server-------snooper--------client. I do some operations on snooper switch (eg: deleting vlan interface, disabling snooping, then adding back vlan interfaces, enable snooping etc). After the above steps, snooper started to receive a bigger value as lease time, which was greater than the configured value.

root@Node1/usr/sbin# cat /etc/dhcp/dhcpd.conf
subnet 30.30.30.0 netmask 255.255.255.0 {
        option subnet-mask 255.255.255.0;
        range 30.30.30.1 30.30.30.100;
        default-lease-time 40;
        max-lease-time 40;
        option domain-name "Domain1.com";
        option domain-name-servers 53.22.53.22;
        option bootfile-name "Bootfile1";
        option tftp-server-name "Tftpserver1";
        option host-name "abc";
}

Here the max lease time is 40 secs, But snooper gets 107 secs, 120 secs in the ACK packet. When I check the offer packet, lease time was always 40. Any idea, what might be happening here? How the operation done on snooper affecting the server?  I examined the packets which are send by server and also received by snooper switch. When I disabled snooping, this issue did not seen and snooper gets the lease value exactly as mentioned in /etc/dhcp/dhcpd.conf.

Thanking you