I can't say if it's critical, but if you have the time, I would suggest running 'VACUUM FULL' instead.
VACUUM FULL fully locks the database, so TIE will be down for the duration of the vacuum, and it will take several hours to complete, but may be able to fix this particular issue. Note that you need to run "service tieserver stop" to bring TIE down, and then "service tieserver pg_start" to bring up just the Postgres database.
That said, if you want to understand the severity of the issue, I would recommend contacting support.
I contacted the support and they said to run these commands which resolved the error.
tie=# SET zero_damaged_pages = on;
tie=# VACUUM FULL ANALYZE
No problems with upgrade after that.