Having experienced something similar with dessert on a recent flight - none was provided until I asked - I chatted with the (very friendly) flight attendant for a bit about the situation. She was very apologetic and said that there are certain items that AM undercaters, so the flight attendants have learned to conserve them for only folks who ask to avoid disappointment. She said that on night flights, the ratio goes as low as only 50% desserts provisioned for the cabin.

I suspect champagne, like dessert, may fall into this category...

Something to keep in mind next time you're interacting with AM flight crew - they might not be trying to be stingy, it might just be that they only have a limited amount of whatever you're asking for onboard.

This of course doesn't excuse AM for undercatering, just may provide a little context for why flight attendants could seem reluctant to break out certain service items, especially in view of others in the cabin. It's not always #shenanigans , sometimes it's just them trying to do their best with limited resources.