The Merseyside outfit took a hit in the race for fourth place by losing 3-2 at Goodison Park on Wednesday evening.
Everton are now one point behind Arsenal, who currently occupy the final Champions League spot, on the same games.
"It is, of course, a big encouragement but there's there's a lot of work to do for us," Wenger told reporters. "Mentally we are in better shape than a week ago because we had two important wins and that puts us in a better condition on the confidence front.
"We wanted Crystal Palace to make a result but you know that in the Premier League it is like that. You can drop points everywhere. Was I surprised? Yes and no."
Arsenal will take on Hull City at the KC Stadium this weekend.