The April 30th Dev post regarding characters says "I’ll note that there was a new marquee/galactic chase character planned for May, which will likely get moved out". It's probably a safe bet that this referred to Shaak Ti. So it may be a Galactic Chase event. Given that normally the character is announced or teased BEFORE the kit reveal, that would make sense too because they wouldn't want us to have advance notice of a Galactic Chase event and which type of energy will be used so people can't stockpile that type of energy.