crobb305 - 1:03 pm on Sep 4, 2012 (gmt 0)
Jez123, have you revised any of your content recently? I see the behavior that you describe only for newer content snippets. The newer the snippet, the more likely I am to rank #1 for it, briefly, until scrapers steal it and push me down. For older snippets (including content that I revised a mere 3 months ago), I'm suppressed to the supplemental body. This gives scrapers full rights to rank with your content in Google.
Penguin and/or other penalties will certainly lead to snippet suppression.