I was reading Why Didn't Dumbledore Take the Sword of Gryffindor With Him to the Sea Cave (Locket Horcrux)?. According to DVK's answer, Dumbledore was a Gryffindor:
If an emergency situation arose where a sword was needed, surely Dumbledore, as a worthy Gryffindor, had the option of pulling the sword out of a Hat.
Is there any canon reference for this other than the argument that Dumbledore was brave?