A CE-560 flight crew failed to cross WENTZ at 1500 MSL as directed on the RUUDY 2 RNAV SID from TEB.

Narrative

[We] departed TEB RUUDY2. Upon reaching 1500 FT; I advised pilot flying that I was setting next altitude - 2000 MSL. Pilot flying asked if he could climb to 2000 FT. I read departure instructions to him to ensure no miscommunication; 'cross WENTZ at 1500 MSL; then via 280 degrees track to TASCA; cross TASCA at 2000 MSL or as assigned.' We were not assigned an alternate altitude. I continued with my after takeoff checks; talking to ATC and following commands of pilot flying. Passing through 1700 FT; ATC advised we were supposed to be at 1500 MSL. I looked at map display and saw we were 1.8 from TASCA or .2 past WENTZ. I believe the pilot flying may have misinterpreted what I read and possibly initiated climb slightly early. I asked ATC if they wanted us to descend back down to 1500 MSL; they said no and gave us 5000 MSL. The rest of the flight continued normally.We had briefed this departure twice on the ground; once during the start-up checklist and one more time holding short of departure runway. We both had been into TEB before and knew this was busy airspace. In the future I will monitor flight path and altitudes a little closer and hold off on some of the after takeoff duties until such time that I feel we are compliant with departure procedure.