You know, I'm not sure why so many people think safewords are there simply for the sub? Even the most experienced couples can have unexpected issues that do not resemble their typical sessions and a safeword is one precaution (note I say "one" precaution ) to help ensure overall safety and success. A friend of mine suffered an annurism (not really sure of the spelling on that) this weekend and there were no outward indications - he had to describe to his partner that there was something wrong and how he felt. They dealt with it based on that - same thing in a session, a Dom/me deserves the safeword and the communication from their sub. It's not a failing, I think it's a sign of respect and depth of relationship.