Piper's initial reaction was to shut the book quickly and jump up, to claim his innocence and hope it worked, but he clamped it down tight as he knew that that action would surly indicate he was not supposed to be here. Of course, he knew he probably wasn't, but that didn't mean others didn't know such things. He did stiffen as if startled though, and looked up, pretending to mark his spot with his finger.
"It's quite all right. I was just taking a break from all the excitement of the ball." And apparently inadvertently snooping, he added silently. "This seemed like a nice, quiet place to do that. Would I be correct in thinking you're doing about the same?" he asked curiously, though he kept his tone polite.