She sang at the right time, but she sang the wrong lyrics. She was supposed to sing この別れが今を覚らせ(kono wakare ga ima wo satorase), but instead she sang この出会いが期待をふくらませ(kono deai ga kitai wo fukuramase) which is Take's line. Even though they ended up repeating the same lyric twice they didn't let it mess anything else up. Such pros!
It's understandable to make this mistake because in the first part of the song, that's the lyric that Murotan sings, but it's switched in the second part.