I'm surprised she would say anything that could be considered a leading questions since that could skew the results. I could see if she asked "Do you participate in any online groups of communities focused around travel" and then maybe another question like "Do you feel that you maximize every opportunity the mileage plan presents?"
But flat out mentioning that other people are part of online blogs and use the program a lot, well that might make you more likely to answer yes to those questions, even if maybe you just posted once on facebook about it or signed up for a new credit card because of it. For good research those questions need to be isolated and not a back and forth discussion.