The veteran stopper was allowed to depart by Barca management, despite proving himself a first-choice for coach Flick in last season's title winning campaign.
Inigo recalled on Cadena Cope: "It's true that Hansi Flick really liked me, but he also knew exactly what I contributed to the team, not only on the pitch but also off it.
"He saw me as a key player, a crucial element in his plans, so when part of that puzzle fell apart at the last moment, suddenly and unexpectedly, it was natural for him to feel some doubt or confusion in that situation.
"He considered me a constant in the team, so every change surprised him a little, which is normal - that's how football is. I think the surprise came from the fact that he found out while I was on the plane, more than anything else.
"Honestly, I didn’t dare tell him right away. There were times when I said to myself: 'Tomorrow, I’ll tell him tomorrow'. Then tomorrow came, and I used to say: 'Later, not now'.
"It was a long journey after the last match: several hours on the bus, a few stops at gas stations, then to the airport, and there, on the way, I spoke to his assistant, Marcus Sorg, and said that I wanted to talk to the coach because I had something on my mind that I needed to tell him. In the end, I decided to talk to him on the plane. And the news really surprised him."