Textures allocation in memory, and continuing about textures topic with GFX card

i had a trouble before performing yesterday night:
the theatre was too hot ( hot air input near the videoprojector) so the thermic fuse blowed out 10 minutes before audience entry.
no time to restart anything ( thanks that the theatre had a ventilator), so i just closed my patch, and restart projector after 5 minutes, and reopen my patch.

This incident shows up me something new with beta26:

I have a lot of textures in memory ( dds + wmv 1440*1050 ) and a lot of images that are played ( classical animation system).

Normally, to hang up everybody nicely, i m obliged when i have open Windows and my main patch to reload each one, effect affect after effect ( calling textures and spreads of quads with textures) to avoid freezing effect when the effect is loaded for first time.

Here i noticed that closing - reopening VVVV didnt unload access to my preloaded in GFX card : no freeze at all, especially on spreaded textures.

So my question is: is it normal that when i close VVVV DDS texture are still stored inside GFX card ?

@joreg: continuing about my topic about textures, and the impossibility to find out and make proof in a little patch about png texture troubles, causing for me lag and bugs on big projects:
i have changed the 5 last png textures lost in the project ( 8x pixel sized based png without compression) to dds format:
result patch is running really more nicely and loading really well. Visually a real difference on loading the patch.
those miserable png where little textures ( girlpower content converted) and one image of 1024*728.