I never thought there'd be a chance to compare Frodo with Stu, but here it is. Like Stu's elation after the "roller coaster" ride, Frodo shows nothing but emotion here. It doesn't seem like he's thinking about much of anything - just being with his friends overrides any thought process. What's happened since their last meeting? Why are they together? How are they together? Where are they together? Who cares?
A case could even be made that he's going "over the top" (reasonable under the circumstances), which might be leading to Merry and Pippin's very gentle restraint. I especially like Pippin's facial expression in #8.
A Stu-worthy hug, too - watch that right arm getting in position to pull everything in (#19). Merry basically lets the hug happen, while Pippin keeps an eye (and a hand) on things.