If the config session was previously at a higher level (set by edit), "save" resets it to the root.
[edit interfaces openvpn vtun0]
[email protected]# save
Saving configuration to '/config/config.boot'...
Personally this is behavior I agree with.
Sorry, the task name was wrong, "save" resets it, "commit" doesn't. Personally I prefer if it'd stay the same, but I don't care if it resets it either.