9.3 - On an idle connection the value of query is the last executed query - which in this case is some form session cleanup command before returning the connection to the pool.
So, it is a normal behavior in Postgres.
One more thing that bothers me, why this idle connection can be stayed idle for 3 days. Is this a zombie process?
You said:
"I am using PostgreSQL 9.3.2 and PgBouncer."
It is PgBouncer that is keeping these connections open and available for immediate usage in its connection pool.