You probably signed a document that permits the lender and/or closing agent to check your employment before and after closing. Reread everything.
Refinances have a three day right of recission, designed to protect borrowers from hasty decisions and borrowers' remorse. Some lenders wait and do the final verbal employment verification at that time, most do so prior to closing. Bottom line, if a borrower leaves their job prior to the end of the recission period, the loan will not fund. Hopefully that wasn’t the case for you!