She will keep asking if you have found Mister Cuddles, even if you have already returned it to her.
pc Experience and Boomers Infamy glitch: After returning Mr. Cuddles to Lindsay, you can gain infinite experience and Boomers Infamy by passing the Speech check (60) telling her that Mr. Cuddles is dead. To reactivate the dialogue line, you have to enter and exit into a building if Lindsay is outside her dormitory or exit and enter again if she is sleeping inside (during the night).
Has appeared randomly at Black Mountain, just wandering around the mountaintop (Mr. Cuddles quest complete, Tabitha & Rhonda reunited) and asked if Mr. Cuddles had been found yet.
Sometimes, she will randomly disappear and thus the quest cannot be completed, but this can be fixed by loading at a previous load and talking to her again.