2012 Toyota Camry - Transmission issues

Hi, recently my 4 cylinder Toyota hesitate when changing from 1st to 2nd auto gears as if the fuel cuts off.
This is not noticeable when the accelerator is pushed hard and when using the manual shifting.
A mechanic changed the transmission oil saying it might help, but did not.
Car has 73K miles.
No light comes on dash.

If you are the original owner I would suggest you talk to a Toyota dealer. I have a 2012 Camry and the warranty on the transmission was extended. I think it was to 10 years and either 100 or 125 thousand miles.