What is a sign that a boy likes u??

last night, i had 2 do something 4 church, so i was walkin down the hall with this kid, and we were talkin. then wen we got 2 the room he said "sit right here!" and it was next 2 him. then i was walkin out of the room wen the cl was over, and he comes up behind me and tickles me right in the sides. is there like any sign or anything that he likes me even tho we like never talk in school or hang out w/ eachother?? thanks.