Whether or not it's because of the warning (and it doesn't seem likely, knowing what you do of dragons), the beast does not return. When Earthbind elapses, there is no triumphant return of beating wings. Peering through the darkness you see flickering shadows and...not much else. Minutes tick by, and you're left with just the wind rushing through the canyon.

As you gather back together and begin inspecting the bridge - absent the threat of hobgoblins - you note that a crack at the base of one of the southern towers which, if widened by force may be enough to collapse it.

Spoiler: OOC
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15 experience for the Deadly encounter this was. Would've been deadlier on your health pools had the dragon not been indisposed!

The hob Veteran had a potion of healing on him, but otherwise those you've killed had nothing of note. If you're investigating north instead of just destroying the bridge let me know.

And if you are destroying the bridge, say how. Slashing weapons probably not the most efficient option :P