Be very careful on what you sign upon leaving. I was put on a PIP after working for about 20 years (and saving their a* several times). I decided to resign before being "PIPPED". Several months later I received a letter from Tempe HR stating that they wanted to recover an overpayment of salary when Toronto switched payment periods (weekly / bi-weekly). This oversight occurred over a decade earlier in 2000, - so they knew this and Tempe H/R thought that I had signed a paper (with Toronto H/R upon leaving) that stated that I would pay one weeks salary back to them. I left without signing any such paper, nor made aware of this matter by Toronto H/R before I left.
*This only added insult to injury, as the wording of this H/R letter from Tempe arrived, stating: "As you are aware, the advance recoverable paid in 2000 was agreed to be taken from your last payment, however, due to an omission, the amount of $XXXX.XX was not taken from your last paycheque".