Your ancestor may have waited to record a document for a variety of reasons. Land records were often filed relatively soon after the document was executed, but some individuals in frontier areas would sometimes wait to file a document because of confusing boundary lines, difficulty of getting to recording office, failure to realize the importance of recording the document.
The example in this image is a relinquishment of an interest in a piece of property which was not recorded until the property was subject to an out-of-state lawsuit decades after the relinquishment was signed. Powers-of-attorney to transfer property are sometimes not recorded until the actual document transferring that property is recorded.
Sometimes deeds of purchase were not recorded until the property is being transferred by the owner or their estate.