Perez himself had been short listed last summer by the French manufacturer's outfit as discussions between his backers and Force India appeared to drag on, although in the end Vijay Mallya's outfit re-signed the 26-year-old Mexican.
"To be honest, I was quite stunned about it," Perez told Autosport.
"I knew Nico was very high on their list and I knew if I didn't go there they'd definitely look at him. They are taking a great driver.
"Only time will tell who took the right decision but I'm happy with the three seasons that I had together with him."
In hindsight, Perez casts a positive look upon the three seasons he spent alongside his German rival at Force India.
"I think we learned a lot from each other. It's time for Nico to move on to a new challenge.
"Nico had been longer than myself in the team, so he probably felt the need to work with new people, something different, to learn new things.
"It was great to learn so many things from Nico."