Thank you for an actual proposal! It makes a lot of sense to me, but there is one reason it probably wouldn't be allowed: the study "implanted" false memories (in the sense that participants stated they believed false memories). I don't think the study would pass ethical review if you were only to follow up days or weeks later (after the supposed end of the study), since that would also be the earliest point you would be able to clear up the lie.
It could probably be tailored to a shorter time period.
A possible great way to do it is have the students originally questioned by grad students, and then the professor themself 'follow up' shortly afterward as a 'check' on their grad student's process. The problem with that is that some of the students may feel incentivized to make the grad student look good.
