DD, 14mo has taken to scratching and grabbing at mine and DH's cheeks and necks when we are holding her. It can be quite painful, which she seems to think is funny, especially if you say 'oww' etc 
It's not that often, maybe once every day/every other day. Most of the time she gives lovely cuddles and is an affectionate child.
We have always been quite firm with her over this, firmly saying 'no' and if it continues putting her down. We have also tried just ignoring her and putting her straight down and walking away.
However, this approach doesn't seem to be giving any results as yet. In fact she doesn't seem bothered at all.
Is this normal/just a phase? Does anyone have any tips or advice for me? I would be very grateful, tia