It has been over 1 year since my home was sold at auction (for more than what I owed). I assumed since my home was considered "abandoned" by the bank and I was told the home was sold that this was considered a foreclosure. However a year later there is still no foreclosure listed on my credit report. It just shows up from the lender as 120 days past due and that it now has a zero balance.

Is there a chance that this will stay off my credit report, or is it just a matter of time until it pops up? The last activity reported by the lender was over a year ago.

If it sold for more than you owed you should get money from the bank. I would contact a real estate attorney. Almost always you can get a free consultation.

To answer your question; there is no way to tell. The lender may not bother reporting it. However, a foreclosure would have been entered in court records, which a credit bureau may pick up.