A thought or sentence that continues the previous statement or thought before the prior compleation of thought and or sentence.
This may be due to either a break in the mental stabilty of one's logic chain, or the possiblity that the subconcious answers the question before the concious mind has fully formed it. Other possibilities lay within apathy or acceptence of the individual.
As opposed to a 'brain fart' there is no time between a) the orginal thought and b) the inturrupting conclusion.
"Do I want to... never mind that would be dumb." i.e. Post-Sequitur
"I want to say... don't you think?" i.e. Post-Sequitur
"Was it my, doesn't matter I don't regret it." i.e. Post-Sequitur
"Watch.. (he'll figure it out) !!" i.e. Post-Sequitur