A spark when I plug my MacBook charger adapter into a power socket

When I plug my MacBook Pro charger into the power socket the power socket lights up and sparks. This removed/burned/scratched the Silver Part tips of my EU Type (double prong) adapter slightly. (This damage is minor. Probably 1-2 millimeters.) Probably sparks from the power socket did it.

Is this normal? Should I worry about it?

These sparks lasts for a second. After that, my MacBook charges normally and without any problems.