At first Ed doesn't really notice, because he's watching her - not his own hands. Automail didn't exactly have the capability to feel something brush against it, so it's not until she's giving him that weird look that his eyebrows raise in question. He was pretty sure he hadn't done anything worth that expression, but he notices she's not even taking the notebook and golden eyes glance down in confusion.

His automatic instinct is to jerk his hand away, and if that dropped the notebook and charger in his panic he definitely wasn't thinking that outcome through too well. A blush stains his features as he glances away as if even that little contact was lewd in his mind, hands now firmly at his sides looking almost violated by the accidental slip.

"Yeah, no problem."

His tone is clipped, about as closed off as his expression. So much for not letting anyone know, and at this point he's more concerned about her looking at him differently now than he was about anything else. Which he was sure would be the exact outcome just based on her initial reaction.