OpenGL runs out of memory

I'm openning several files, and some of them a are scanned copies, and the average number of pages for those documents are 50 pages (each page of 612x792 px), but at some point, I'm getting the following errors :

D/OpenGLRenderer(11526): GL error from OpenGLRenderer: 0x505
E/OpenGLRenderer(11526): OpenGLRenderer is out of memory!

The application doesn't crash but it just display a blank (black) image. Any tip about how tp free some memory?

I'm using the 3.2beta1 library.

to be ensure: only 1 PDFReader opened at one time.

There's only one reader activity at a time, the issue appears when the user is changing between pages, and if the user close the current Reader activity and open a new new.