Yes, mgcsinc. They have not published L fares for sale for the Dreamliner IAH-DEN, from what I have seen so far. They have published them for other aircraft, even G fares. But so far, the lowest fare I have seen for the Dreamliner is a T fare.
You're not understanding the nuance between published fares and availability. With very limited exceptions, there's no such thing as "not publishing" G fares for a specific aircraft type or specific flight.
Highly suggest reading this series of articles:
http://hackmytrip.com/2012/02/unders...ine-inventory/