My son also had one.
Have you had an ultrasound yet?
My doctor told me that they wouldn't do ANYTHING about it unless 1) the ultrasound showed that the tube had closed up, and that the testicle was "trapped" in his abdomen, or 2) it hadn't dropped by the time he was two years old.
Our ultrasound confirmed that the testicle could move freely up and down that tube (making it sometimes descended, and sometimes "undescended"). Once the ultrasound showed that it *could* come down into the scrotum, she said "don't worry about it until he's about 2". It descended and stayed down there after a few weeks.
What are your dr's reasons for only giving it 9 months?