Local dodging with filters is a practice many have used.

If you are getting a magenta cast in hair when everything else is correct your process is off.
Contrary to what you are being told this is not what one would expect with correctly exposed film and process colour negative.

If this is isolated case then don't sweat it too much and try dodging out the unwanted colour, if this is happening to all your film, you should revisit how things are being done.

good luck