TL;DR This is normal operation for power supplies in a dynamic system. There isn't much you can do to "fix" the voltage overshoot.
Overshoot is quite common in electronics when a power supply ramps up to match a load and then briefly exceeds the requirements and then has to pull back.
It is a feature of every adaptive system that uses a feedback loop to control their output.
More information at the Wikipedia page on overshoot.
This EE.se question Exact definition of overshoot
The essential problem is that when load increases on the output it causes a voltage drop at the power supply. This voltage drop causes the power supply to adapt and increase current (which increases the voltage out).
The problem is that for fixed loads the actual current drawn is dependant on voltage. If the voltage drops then it draws more current, as the voltage is increased by the supply then the current draw falls.
This change in current and voltage causes the apparent load to change in a way that is hard to compensate for. By allowing more current through the voltage will rise to a "good" level, but this will mean that the device no longer needs to draw as much current and causes it to show a lower load and the voltage rises further than expected. The supply then clamps back so the voltage drops slightly and the current increases again, causing voltage to droop again.
This cycle repeats until both supply and load settle down.
