Was it a Bunyan or Sitonai though?

Sitonai is story-locked. That means if she didn't have rate up, she won't showed up at normal banner, so definitely not Sitonai.

Well if they have her unlocked its possible.

Not in this banner. This banner didn't have Sitonai as "rate up" servant, so it's not possible to get her from this banner.

Really? So story locks can't spook? Huh.

The only time when story locked servanst can spook you are on special banner, like this year's Chaldea Boys Collection (only males tho)