Jean-Philippe Mateta and an own goal from Nathan Collins saw Palace win 2-0 at Selhurst Park.
Andrews said afterwards, "It was a game of very few chances.
"The first goal was a set-piece where they get first contact and second contact, so we’re clearly not going to be happy with that as we set the bar very high with set-pieces.
"We didn’t hit the heights that we have in recent weeks individually and collectively, but you have to factor in the opposition and how they tried to stifle the game. We huffed and puffed a little bit, and didn’t really have that real conviction to our play."
Veteran Bees midfielder Jordan Henderson also said: "It’s a difficult one to take.
"I don’t think there was too much in the game. Two set-pieces, we’ll be disappointed with that – it’s been our strength of late.
"We’ve got to analyse the game properly over the next few days and work on the things we need to improve on for Newcastle."