Well, I agreed many months ago... 'cause I didn't read it. Now I just finished "elementary school" and noticed that:

From the deviantART Submission Agreement [link] :

[...]the parties hereto hereby agree (and ratify past submissions) as follows:
[...]
3 . License. to Use Artist Materials. Artist hereby grants to deviantART a worldwide, royalty-free, non-exclusive license to do the following things during the Term:
[...] 4 . the right to sublicense to any third party any of the foregoing rights in the Artist Materials, or any part or element thereof, subject to the terms and conditions of this Agreement.
[...]
14 . Miscellaneous.
[...] 6 . Survival. The provisions of Sections 1, 3(e), 4(b) 5, 6, 7, 8, 10, 11, 12, 13, and 14 shall survive any termination of this Agreement. In addition, any sublicenses granted to third parties for the display of Artist Materials on electronic devices pursuant to Section 3 shall survive any termination of this Agreement.

That's why my gallery vanished.

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En castellano:

Punto 3.4.:
DeviantArt puede sublicenciar las obras de un artista de DA sin avisarle (porque ya tiene su permiso al haberse hecho la cuenta) a terceras partes de todo el mundo, con derecho a cobrar por ello, y sin que el artista pueda reclamar una parte (royalty-free)

Punto 14.6.:
Cualquier sublicencia que haya hecho DA con una tercera parte para reproducir las obras de un artista por medios electrónicos (ej.: webs, logos, etc.) sobrevive a la finalización del acuerdo entre DA y el artista.

Espero que en futuros contratos no me marquen golazos como este.