"Admit" is a gerund taker and the gerund can connote the action happened prior to "admit". So "she admitted making a mistake".
1. She admitted making a mistake.
2. She admitted cheating on the test.
(Did the action "making a mistake" happen prior to "admitted"? Did the action "cheating on the test" happen prior to "admitted"?)
Yes. Making a mistake and cheating happened prior to the admission that she did it (in the past, be that in the last few minutes or last year, whenever).posted by Reed