WijnaldumK won a recall for the European Championship qualifiers away to France on Friday and at home to Gibraltar next Tuesday having been included in the first squad named by Koeman who has returned to take over from Van Gaal.
A broken leg on loan at AS Roma last year meant Wijnaldum missed the World Cup in Qatar but he had already been dropped by Van Gaal because he had not been playing regularly for his parent club Paris St Germain.
Wijnaldum said he had secretly hoped Koeman, who had his birthday on Tuesday, would return to the Netherlands post after he quit to become Barcelona coach before the last European Championship.
Koeman tried to sign Wijnaldum for Barcelona from Liverpool and Wijnaldum said he had not forgotten that.
"Unfortunately, it didn't work out. Our bond goes back to our time at Feyenoord,” he told reporters on Tuesday.
Wijnaldum said his relationship with Van Gaal was more complex after starring at the 2014 World Cup in Brazil under the veteran coach but then being dropped last year.
But the midfielder insisted he held no grudge.
"I accepted it at the time, and we had a conversation about it. I’m also grateful to Van Gaal for what he has meant in my career.
"It's not as if I don't like him now or do not rate him as a good coach, but with Koeman I have a better feeling than with Van Gaal."
With Koeman's return, Wijnaldum hopes to reclaim a key role in the Netherlands side, especially after recovering from his injury and beginning to playing regularly at club level. His loan move to Serie A came after an unhappy spell in Paris.
"I felt that Roma really wanted me and that (coach Jose) Mourinho wants me to play a lot. And also that the squad were happy with me. I also felt that when I came back from my injury."
With midfielder Frenkie de Jong (25) missing the matches against France and Gibraltar through injury, Wijnaldum is expected to feature more prominently in the team.
He said he was still "hungry" for success. "Certainly, because we can make progress with this team. There is plenty of potential," he added.
