Worth watching this thread as WordFence tries to get this resolved:
http://wordpress.org/support/topic/you-checked-in-code-to-the-258-akismet-tag
Worth noting that this is unrelated, and shouldn't have caused a problem at the time (as it was made before 2.5.8 was released).
The latest issues are that Wordfence doesn't recognise the new 2.6 version of Akismet (and will require an update from Wordfence to stop the alerts)