I thought Marion was presenting a supportive front to hide how irked she was. The description of her reaction made her seem like she was celebrating gently and remaining composed instead of wildly showering Mor'Lag with alcohol.
Mor'Lag needs a pick me up. Hopefully the title comes with some perks.
Seems like Mor'Lag either intentionally saw through the guise by using great perception or accidentally pierced the shroud by expecting disapproval and derision causing them to become unreceptive to praise or encouragement, leading them to think Marion was being sarcastic.