Nah, I thought the same, probably cuz I look at the pictures first, then look at the dialogue, so I can visualize what is happening as I input the words.
Also, the only real way to tell what was happening is through the words on the last panel. the whole "If you're older" thing can stir you the wrong way, should have been "When you're older".
Also, for some reason, it looks like the little sis is the one attacking the grandpa; the first (one on the left) shadow looks smaller then the second one (cuz the second is slanted more), then there is the whole hair thing, as his grandpa is bald, and it seems like the first shadow has bangs. Though it could have been him fighting his gramps (the whole Stay away from me!!" bit.