Welcome Brodee. I think you may be recalling two different episodes. The time when Andy smoked in bed is from 'Gomer the House Guest', from season three.
In 'Mr. McBeeVee', from season four, Andy lights up after talking to Opie about his new friend, Mr. McBeevee, a phone lineman Opie met in the woods and whose description Andy finds hard to believe.
Good to have you aboard, Brodee and please don't be a stranger!