I ran into this at the IRS and, if it applies, it might explain why they took the RMD over part of the balance:
Apparently the old rules for 403b type plans set the required withdrawal at age 75 and the laws were changed in 1987 to age 70 1/2. Under certain circumstances the amounts in the account prior to 1987 might grandfather to age 75. I don’t know if this applies to me or not but the numbers come out close with the estimates used.
And it is also possible that I totally don’t understand what I read at that link so I still need to follow up with VALIC.