I've had a very similar problem. Twice about a week ago one block from home with a cold engine the shift from either 1st to second or second to third was very hard. It was quite a surprise. Then Thursday at lunch with a warm engine taking off from a stop I was at 3,500 rpm before the shift into second at about 5 mph. Friday I had the same high rpm takeoff from a stop happen twice. Drove 200 miles Friday night, 200 miles Saturday night, around town toady and no problems.