The idiomatic expression "last-minute surprise" refers to an unexpected event or development that occurs close to a deadline, with little time left for preparation. Full definition
We have a reputation with insurance companies and defence counsel for staying on top of our files and sharing information to avoid last minute surprises at the negotiating table. (camllp.com)
Oh well, I was hoping for a nice last minute surprise from uncle Ebenezer... But i should know better than that.l Where there's hope, there's always dissapointment.? (justarsenal.com)
Any problems with a home should be either repaired or disclosed, and I always advise my clients to do so, as last minute surprises turned up by home inspections often cause a sale to fall through. (thestaginglady.com)