Wrasse(s) hiding/missing

[SmallFry]

Ive read before that wrasse are inclined to hide for a while after being introduced to a tank, is it normal though for them to do this when other fish are added to the tank?

I added a Coral Beauty and a Kole Tang to the main tank on the weekend. I didn't notice any aggression but the next day I noticed that the two wrasse were hanging around up in the corner up by the power head. A day later I didn't see the flasher wrasse but the ruby headed fairy wrasse was still out and about. It's now Friday and I haven't seen either for about three or four days. I have lids on the tank and can't see any evidence of them having jumped? I could se one jumping or just dying, but two at once?

I am thinking or rather hoping that they're just hiding rather than anything else.

How long can they stay in hiding for - I haven't seen either at feeding time and the tank is new so unless they're finding uneaten food when the lights are out they haven't eaten...