Littlepip's overly humble attitude makes more sense and feels a lot less like a cliché good guy trait when you remember that, back in Stable 2, she had no friends; the only thing she could do to pass the time was clean up a room, occasionally fixing a PipBuck or two; she's a lesbian and it's very likely no other mare in the Stable swung that way; her mother was a neglectful alcoholic; and, as she pointed out early on, her cutie mark was of quite possibly the most common piece of equipment in the Stable. She probably didn't have even a shred of self-esteem when she walked out the door. And out in the Wasteland, being forced to kill to survive made her feel like a monster as opposed to a hero, so she couldn't even take pride in her victories.
Silver Bell had a balefire bomb right in her barn for who knows how long. An armed balefire bomb at that. And she's a child. One little slip up, and...
Slip up, shmip up. It was pretty heavily implied that she knew exactly what it was and was planning on committing suicide with it after one last, big party.
In chapter thirty-four, a dying bandit tells the people of Arbu, "You can't... have... my son..." This seems perfectly normal, until it's revealed that the ponies of Arbu are cannibals. What's more, according to Grandpa Rattle, a good portion of the aforementioned bandits are former residents of Arbu. The dying bandit knows what they're doing. He isn't saying, "Don't take my son." He's saying, "Don't eat my son."