Probably not. Power supplies like the 18w charger use switching technology rather than traditional transformers that switch current on and off just enough and at a high frequency to charge a capacitor to the target voltage. The minute surge of current through components, particularly the small isolation transformer can cause vibration at the high frequency. Steps are taken to minimize and dampen the vibration, such as caulking but that's not always 100% effective.
When the power supply is not under load, the squeal can be more pronounced.