I'm pretty sure that there were only three last year and the year before too. I think Lee and Misti were changing the timing a bit because there was reduced participation at holiday times.
If you look at the archive of galleries, in fact 2013 was the last time there were four on a more or less quarterly basis.
Stampin Up! Gallery: Virtual Stamping and Scrapbooking Nights - Page 1 - Cards & More - Splitcoaststampers
Try pm-ing Kim, Berlycece, if you want a definite answer.