Large rat too big??

[Lolo76]

My big girl Mona is around 2300g, and I usually give her either 1-2 small rats or 1 medium rat weekly... but today I bought her a (smallish) large rat, since the medium ones looked kinda puny. She had no problem killing it, although it did take longer than usual, but then she couldn't swallow the rat. She tried for a good 10 minutes from all angles, and eventually dropped it in frustration and glared at me - seriously. Luckily I had an extra small rat (refused by another snake), and she ate that instead without any trouble.

So, apparently a large rat is too much for even a BIG ball python? Or was it just because she's only had small/med in the past? Anyone here feed large rats, and if so, how big is the snake? Just curious! And a bit annoyed about the wasted $6, since there's no way any of my other snakes could've finished it off.