Just to clarify, you can get a copy (or at least I did) of the ROFR waiver from the Orange County Comptrollers site. Follow the links to eventually search for and find the recording of your sale. You can download the warranty deed and ROFR waiver.
Now, who can tell me what the estoppel is and how do I get a copy of it? For a while I thought it was the ROFR waiver based on a Wikipedia definition of estoppel.