Still dont think that should cause it to go bad so soon as Ive always
That's the problem with your line of thought, right there.
Your rice has always been unsafe. For safe rice, you have to cool it down to under 4 Celsius within 4 hours of being cooked.
Unsafe food will sometimes spoil, sometimes won't. It will sometimes make you ill, most of the time do nothing. And the two conditions - "spoiled" and "will make you ill" are only weakly correlated, you can get sick when unsafe food looks and smells perfectly OK.
Predicting what bacteria will take over unsafe food, or retroactively explaining it, is as difficult as predicting the weather. So a literal answer to your question (why did it happen now when it hasn't happened before) will take mountains of data and weeks of developing an appropriate model. Also, there is no way to give you advice under which circumstances to expect it - as long as you don't follow food safety rules, it can happen any time.