Little boys private parts

I took my little boy to his newborn checkup but he was 7 months old as my doctors was backlogged. They done the usual checks however when checking his testicles the doctor could only feel one, has this happened with anyone else ? Been reading it on the nhs website and it’s saying if they both haven’t naturally dropped by 6 months then he will need an operation before 12 months and he’s currently 9 months been waiting for an appointment at the hospital for the past 2 months.