No harm in using 0w20, but I suggest you stick with the Recommended oil grade 5w30.
On the next oil change, I suggest you change it with Caltex Havoline Fully Synthetic 5w30 and then observe its performance, as your car is new, I don't think it should do any such thing as changing the color of oil in just 4500 kms.
The rest is your choice.
I hope it helps.