Whenever you collect a Dragon Glyph, you don’t need to run to Dragonriding Trainers to learn the new talents. Talents can be unlocked on the go.
Click the Dragon Isles Summary icon located on your minimap.
This will bring up the Dragon Isles Summary Window. Click on “View” Dragonriding Skills & Unlocks to open the Dragonriding Talents tab.
Here, you can spend all your glyphs on talents without visiting the Dragonriding trainer.
Source: Reddit