Not a negative indicator at all. She got a more senior job (SVP, Corporate Communications) at a private company which looks like a potential IPO at some point. Assuming she got some stock or options befitting her title, the move could be quite lucrative. I thought Julie was an excellent IR person, and I miss her comments and insight. But her departure is in no way a negative indicator for MITK.
First, her position was not what would be considered a key position. Maybe it was time! The most likely answer to your questions could be:
The company feels like it is finally time to get their story out on a more widespread basis. They may believe that they now have the fundamentals in place to support interest from more sophisticated investors than the retail community. The Blue Shirt Group has more connections to the investment community and I myself consider it a huge positive as they are now trying to stoke interest in the company. They have a story to tell and they are going to have results to back it up!
Julie was from Blue Shirt Group. Not sure if Mitek hires the person or the firm when it comes to IR.
Did she leave or was she fired? We don't really know what the circumstances were of her departure nor will we ever find out. As long as the new guy is doing his job, life goes on.
I will concede that abrupt departures at any company are always troubling to investors, but that feeling may be wholly unwarranted.