No it's not. It's secure but not reliable, your ssh tunnel will disconnect at some point. Use firewall and/or native security.

Thanks! I read somewhere that this was a good way to secure redis for compliances. Good to know it may not always work.

That's what the firewall is for. I set up iptables rules on all machines that only allow fixed IPs on the local network access to specific ports.

If you're running it over the public 'net, then I think Mongo and Redis allow for username/passwords and/or encrypted transit.