Yes, different from the o-ring on the filter, though the same basic idea behind it.
The multi-port opens up after you remove a couple of bolts and disconnect the handle. There are several parts that you need to keep straight so you can put them back when reassembling, but otherwise it isn't all that difficult. If you feel up to it, you could take it apart and check the o-ring and the surfaces it presses against and make sure there aren't any nicks or cuts and everything is lightly lubricated with a silicone based plumbers lubricant. Depending on what you find, you may need to replace an o-ring or two.