Oh yes, I've come across that one too mummsymags
Stansgran, I'm not sure that it is exactly. From what I've read aposiopesis is a device whereby words are left off for dramatic effect, or because the speaker cannot complete their sentence due to any of a number of emotions, such as fear, anxiety, excitement etc., and leaves it hanging, or quickly moves onto another thought.
Some of the examples given could fit that description, while others are just fashionable contractions, nothing to do with emotions.
And yes I agree, as this thread progresses it is developing a rather 'pedants' corner' feel 