She didnt think she had the right to be First Minister - All parties put forward their suggested person to be First Minister, Labour AMs all voted for Carwyn, all Plaid AMs voted for Leanne , but also the conservatives, UKIP and everyone else also voted for Leanne - which meant she would have been elected First Minister by 'consensus' it was only because Kirsty Williams voted for Carwyn that he survived by the skin of his @rse, otherwise he would have lost - that's politics and those are the rules.
The result being Carwyn is now sunk until he can cobble together some ideas which will make the other parties vote for him - he should not have taken the electorate for granted.
Here is a video that explains it
http://www.bbc.co.uk/news/uk-wales-politics-36269221