These look like badpixels that haven't been patched. This is probably because the software you are using doesn't support DNG 1.3 badpixel opcodes. If you switch to DNG
1.2 1.1, and create badpixel.bin from the menu, this problem should go away.
If you want to fix the existing files, most Adobe tools should know what to do with the badpixels.
edit: corrected version