In /etc/fstab, be sure to add the option:
As it will attempt to start the network mounted sshfs before networking has been started.
The entire line looks like this:
user@host:/some/dir /local/path fuse.sshfs defaults,idmap=user,_netdev 0 0
From the man pages:
The filesystem resides on a device that requires network access (used to prevent the system from attempting to mount these filesystems until the network has been enabled on the system).