Before Yuzuru skated Seimei,while waiting for Jun Hwan's scores he found a hole in the ice. Which he alerted the referee about it to get it fixed.
https://twitter.com/yz_1207_17/status/1226388090043764736
This should be the "something unusual" that happened that Yuzuru mentioned during the press conference. It effected his concentration. The hole was at where he did the 4T+1eu+3S I think.
Olympic channel article which referenced the hole :
https://www.olympicchannel.com/en/stories/news/detail/hanyu-yuzuru-win-maiden-four-continents/
Later, Japanese media reported that the hole was deep till can see the concrete underneath.
https://headlines.yahoo.co.jp/hl?a=20200209-00000066-jij-spo
Abt Yuzuru's sentiments/feelings, he said he's happy to skate something that's him. Easier to upgrade tech difficulty -> where to insert which jump, skate according to tempo(which is important for him). This should be the interview after SP.
For me, I prefer him skating Seimei over Origin & was curious what changes were made to make it fit 4 min. Origin, somehow each time I'm reminded of Plusenko's version.