Summary: Users are not able to change one of the recurring events from an invitation.
If you try to change this one event occurrence from Tuesday 4/18 (the event happens every Tuesday) to Wednesday 4/19 - it only asks if you want to send to existing guests (it is NOT asking the three options, that is - only this occurrence, this and future, or all).
It will then change the current and all future occurrences to the new date or time.
Now, it is noticed instead if you change the time in this example. That is, if the meeting is 3 PM, and I change it to 4 PM without changing the day - Tuesday the 19th itself, it then gives you the three options, but not when changing the day.
Workaround: (to change only one event in the series) is to drag the affected event and drop in the new date/time of your choice, however, this workaround will 'break' the series, meaning that the events prior to the recurring series 'dragged' including the event 'dragged' will not have any further relation to the events moving forward
For more info, please refer to internal ticket #6921 and #6933 and Google case #12510460