You are correct. Versions 270, 268, 265, and 262 were bug fix only releases. It appears that we might have reset the readme with the .271 release, but the high level breakdown is as follows:
270 - single fix for a crash that could occur with flashplayerupdateservice.exe
268 - stability fixes, in particular for mozilla firefox and flash player's protected mode
265 - stability fixes, audio fixes
262 - stability fixes for protected mode
Still, Release Notes' Version History section need to be updated.
Flash Player 11.3 User Release Notes:
The above still not updated and it would appear it won't be... due to the new release?
Flash Player 11.4 Release Notes: