Had it happen once to me when in J. FA said I needed to store in the bid as "computers aren't allowed in the seat pockets." I think it was an overzealous FA as it doesn't make any magic. I could put a 10 lb textbook in that pocket that would pose more risk than a laptop, let alone an iPad.
Reminds me of
Time to review "eletronic devices" rule.
Why isn't it permissible to use an iPhone
in airplane mode during take off and landing? It's smaller / lighter than a regular book and it would pose 0 risk of interference with communications equipment (EMF from cabin lights would pose more of a risk). After reading EnRoute for the millionth time, one could really use some Angry Birds during take off and landing.