For what it is worth I use both, in much the same way as you do, and I haven't been arrested or charged yet.
I really don't think that there is any body with the power or authority to give or withhold permission. I suggest that you do what you think is appropriate. If people really don't like it they'll let you know, and you can decide to change or not depending on whether their reasons make sense.
I like the way you do your ebooks.