She might be about to ovulate... or maybe she has already and you just missed it. She is definitely ridge backed.
To the post above (sookieball): I think that is a 28qt tub, if so she's about 1/3 the size of it, so I'd say she's probably between 1500-2000g, which is plenty big enough. I could be way off. The tub just looks alot like my 28qt. tubs, and if so she would be plenty big. Pictures are usually deceiving when it comes to telling the size of a snake.