He was not sure, he advised to keep checking in the tracker. Basically what oath ceremony could be changed due to schedule reasons but the best would be to wait for invitation by email which would be a week before the date it shows.
Unless you are an IRCC officer you including everyone here can not be absolutely sure about why’s. I would categorize your views just as a speculation than an affirmative reason behind the applicant’s case.
I am no expert, but there could be various reasons -
a) Travel history
b) multiple passport evidenced.
c) Luck ( plays a major role at times with no rational)
Dont think any issues to be worried about. just a casual conversation about your passport, that's what happens in interview based on what I have heard. you prohibitions / language etc are all in progress ?