Perfect Crime bug or the text is wrong.

Saboteur's Perfect Crime node that says traps have a 20% chance to trigger an additional time may be bugged, or the text needs to be fixed. Perfect Crime will not ever trigger traps an additional time if they expire. I've been told that traps going off from expiring isn't "triggering" but since Chain Reaction and Pyromaniac can trigger from expired traps I would assume Perfect Crime does as well.

Perfect Crime will only trigger from enemies, or Chain React, and never any other time, so this is either a bug, or the text is too vague. Although probability does say I could just be that unlucky, but I doubt it.