[Koha] New to community-Deleted records in search results

Hi, I'm Kim Bevis at IDA CCR Library in San Diego, CA. My organization installed version 3.18 of Koha via Equinox in June 2015. To clean up the catalog, I have had to delete large numbers of bibliographic records. Last week the deleted records randomly began to remain in catalog search results. When deleted record is opened from the search results list the following error message occurs: The record you requested does not exist (11158). Maybe an to be an indexing error? Thanks.