New dog is coughing ?

i got a new dog on friday he is a mastiff/lab 11 months. he was coughing at like 6 am i would say today . this is the first time i have heard him cough. the lady said he had all his shot, but she had no proff so it could be a lie. i had the windows open and he has not coughed since then. is it just dry throat or kennel cough no discharge or anything. if its kennel cough will the shot be effective on what he has now