I've had this condition for years but my doc said it wasn't unusual since I have allergies, eczema and asthma. I've always just called it 'skin writing' since it's easier to remember!
The best thing about it is you have a pretty cool party trick, plus you can amuse yourself easily if you've got time to waste, the worst thing is the accidentally scratching your face and having strangers come up and exclaim 'Oh my God! What ever has happened to you???'
Antihistamines work well to reduce the effects but they only seem to control it temporarily.