I think all of that was him being directed to playing out a role as a Master Jedi. You have to remember before those movies the only actors that were able to really flesh out how a Jedi acts is Alec Guiness as obi wan and a puppet name Yoda. It was new territory. So you get this plain mannerism that is calm but absolute. Samuel was trying to convey that somehow and it just came out odd, probably partly because it was motherfukkin Samuel L Jackson doing it. Where as when Alec Guiness did it, the oddness just worked with the actor.