Yes that is abnormal.
When you say "first layer" do you mean you are adding plaster on in layers?
If so, I advise against it. The plaster won't lock onto another layer of already cured plaster. (usually) When you make a plaster mold you have to try to get it all in one shot. But if you just meant that the first layer was the first half of a 2 piece mold, then never mind.
Your plaster has not cured because you:
A) mixed in way too much water
B) the water you used was very cold
I am willing to bet it was both. It really sucks when plaster doesn't cure fast like you want it to. To speed up the process get a fan to blow on it. Heat isn't necessary at this point. You just want the moisture out of the mold. It will take time. Be patient. IMO I think you may need to start over IF you were trying to do several layers at different times.
Good luck!