He knows that Shadow had wanted a lot more from him, but at the time he didn't feel that it was appropriate, or the urge to tease him some other way always cropped up. Of course, now that the little bastard was practically blushing his face off at him, well - might as well go along with it~
He's always surprised when Shadow actually goes along with something that he's up to, considering the hedgehog is usually protesting everything else - but he tilts his head and lets him nibble along his neck, something that makes him purr gently. That's a good boy~
Nuzzling at that neck, he shifted his teeth from fur to Shadow's shirt collar, tugging it back a little so he could get at the curve of where neck meets shoulder, helping himself and nibbling there next~