DNS Server for BIG-IP Management Changing in AWS

I currently have two BIG-IP LTM Virtual Edition boxes running in AWS. I have configured the boxes manually to use two of my DNS servers. I'm using this so that when I create nodes using the FQDN option it uses our existing DNS setup (I know we can run DNS on the F5s, and I'd like to do that eventually, but I need this to work with our existing setup first). I'm adding the IPs of our DNS servers in the DNS Lookup Server List found in the System > Configuration > Device > DNS section. It works when I first set the servers, however after some time it reverts back to the DHCP-supplied DNS servers owned by Amazon.

I checked the /etc/resolv.conf file and it lists the correct DNS servers, so I know that my change is working, if only temporarily. I've tried to replicate the issue manually by restarting the DHCP client by issuing the command

bigstart restart dhclient

but when I do this, the DNS servers do not change, so I'm not sure exactly what is causing this. Do I need to change the management interface to static from DHCP to avoid my DNS configuration from being overwritten?