a right hand drive car gently pulling to the left over a distance of about half km when the wheel is let go is perfectly normal. They are manufactured like this (read the alignment machine as proof, you will see the caster being slightly off on the left side - meaning the left wheel sits just a hair behind the right wheel)
This is done as a safety system.
left hand drive cars do the exact opposite, they very gently pull to the right when the steering is let go.