Tip of Nozzle is black / burnt

[lu.1]

Hei,

I am new to 3D Printing. Just switched to another nozzle and noticed that my .4 nozzle is black / burnt at to tip and little bit at the front. Tried cleaning it with a copper brush but did not help. Really baked on.
Is this normal?

[lurker93]

maybe? not sure if you can share a photo; this is what my 0.4 nozzle that came my A1 looks like after a few days of printing (maybe around 0.5kg of filament?).