I think you're right. I think she had no idea she was icing up.
Any time I'm in cloud, and it's anywhere near freezing, I'm looking out the window about every 30 seconds straining for any sign of ice on the wing or wheel. At night, I'll be shining my torch out. I'm astonished that others would not be doing the same; ice is bloody scary.
It did take my by surprise once, at 9,000ft over Nigeria of all places. Normal cumulus clouds, 30+ degrees on the ground; didn't even contemplate the possibility of ice!