I myself had often wondered about how this lasting punchline about Iowa/Brands supposedly owing a trip to State College came about so I did some legwork. Here's what I have found:
Starting my search in 2000, Iowa and PSU wrestled and rotated every year until 2011, 6 home and 6 away matches with PSU hosting in 2011. In 2012, PSU hosted again, making in two in a row for PSU. The next year,(2013)they were not scheduled, which led to Brands and Cael having a twitter convo(below) in which Tom brought up that PSU owed them "two in a row", which Cael agreed and Iowa hosted.
Following years:
2014-Iowa
2015 -PSU
2016 - no match
2017 - Iowa
2018 - PSU
2019 - no match
2020 - Iowa
2021 - canceled - scheduled at PSU
As best as I can tell, the only discussion about the years where they weren't scheduled to wrestle (13,16,19) happened in 13. That year sure seems like it was understood between the two coaches that it would be in Iowa City to make up for the back to back years at PSU(11, 12).
It's possible that it happened, but I couldn't find any info about the two coaches having conversations in 16 or 19 to set up a dual. If anyone has that info, it would be very helpful...
Otherwise, my best guess is that over time, people only remembered that Cael and Tom worked together to schedule a meet when they were not on the schedule in 13, and that it was in Iowa City. Therefore, the next time they were not scheduled, it should happen and at PSU. However, if you look at what was actually discussed, the one and only time they did this, it was clear to both coaches that this was a make-up dual in Iowa City and the hosting was back to even...