The person you should be asking is your friend. It's not normal. First, you should find out whether your friend is aware of his strange sounding sentences. If he is, and says that he's trying out new literary techniques, then that tends to rule out a whole lot of potential causes like acute brain pathology (delirium from drugs, brain tumours, schizophrenia - or he could just be tired - the list is almost endless).
If he has no idea what you're talking about, there could be a problem.