The 42 age cut off is so that you can accumulate 20 years as an officer by the age 62. So I would assume if you are prior service officer that time would count...(so as long as you are able to get 20 years combined as an officer it should not matter but we all know how fickle the military is)...just verify everything and make sure if you sign a contract you get everything promised in writing.
Example. You could sign up to go to anesthesia school and if you fail you are still obligated for the full time you signed up for and get assigned to their needs not yours.
OR if you sign up for a critical care add on make sure you have it in writing. Just some things I have heard when speaking with people.