Heroku not listing pg_search_documents table - ruby-on-rails

Question

This is pretty weird but for some reason, heroku doesn't seem to show the pg_search_documents table when when I list tables using the heroku-sql-console.
>> heroku sql
SQL> show tables
+------------------------+
| table_name |
+------------------------+
| activity_notifications |
| attachments |
| businesses |
| color_modes |
| comments |
| counties |
| customer_employees |
| customers |
| delayed_jobs |
| file_imports |
| invitations |
| invoices |
| jobs |
| paper_stocks |
| paper_weights |
| quotes |
| rails_admin_histories |
| schema_migrations |
| tax_rates |
| users |
+------------------------+
As you can see, no mention of pg_search.
Then, in the same session,
SQL> select * from pg_search_documents;
+---------------------------------------------------------------------------------------------------------------------+
| id | content | searchable_id | searchable_type | created_at | updated_at |
+---------------------------------------------------------------------------------------------------------------------+
| 3 | Energy Centre | 3 | Customer | 2012-12-03 19:33:55 -0800 | 2012-12-03 19:33:55 -0800 |
+---------------------------------------------------------------------------------------------------------------------+
It's also interesting that the show tables command lists only 20 tables whereas heroku pg:info says there are 21.
The reason this is a problem rather than a curiosity is because I can't get heroku db:pull to pull down the pg_search_documents table (everything else pulls fine) and I can't test migrations on production data.
I'm using PG Version: 9.1.6 on heroku and PostgreSQL 9.2.1 locally. Also PgSearch 0.5.7.
Any ideas what the issue is?