Would it be a problem to show the past month's activity? Or, at least 14 days? That would cover, say, a week's vacation/trip somewhere, plus a few days before/after for the weekends.
I could even display all of them, I was just afraid it would bring out too much useless output. I am changing the code to display all the referrals. If I see that it grows too much or someone complains, I will show last 10 referrals, no matter when they got invalidated, and a link to see all of them in another page.