Yay! I get to spend 5 hours figuring out how to update the syntax for my pf.conf rules.
There is only one entry in http://www.openbsd.org/plus60.html so I would assume you don't have to change your rules. Also pfctl -n should tell you.
"In pf.conf(5), change the parser to make af-to on pass out rules an error. This fixes a bug where a nonworking configuration could be loaded."