Ford Falcon 96 El Automatic gear problem

Hi i m mew here! I got this Ford station wagon with 250000km on there.Had it for a year and absolutly love it. but now the last 2 week when the motor is still cold and i stop at intersection or traffic light. I press the excellaration and the car wouldn't gear in. well after taking the revs normally down again it click into gear. what is it clutch worn? but when the car is warm after 10 minutes the problem is gone