Personally I believe she kissed her hair, it seems the natural thing in that situation. Or if not kissed, nuzzled a bit. Actually saying "I love you" probably would have produced a big blush or more, given this is the world of Everyone Freaks Out About Everything (which actually put me off in the early chapters).
Mind you, the everyone freaking out factor kinda makes Chika's ending palatable, since it's consistent with the story and how she/everyone acts. What I don't get is the sudden aggressive obsession of Random Boy, who hadn't shown anything like that earlier. To me that was what came out of left field.