Why ex boyfriend takes forever to text back?

this morning i was texting my ex bf and he was being sweet and cute and nice and texting back less than a minute or so and was being flirty too..than i said brb cuz i hav to go drive..i texted bk sayin i bk and he did short words lik one words sort of...than he wouldnt text me bk for an hour than he did and said he took an ice bath..than he started texting me lik uk long stuff i guess and so on than he wouldnt for another hour so i decided to text a message tht wasnt for our conversation and he replyed right back so whats going on???