LDW
I'm not ex-RAF but I have done a large number of spins in the Bulldog. Spin recovery is absolutely standard BUT, unlike some types, if you don't do the right things the recovery will be delayed - in that way it's an excellent spin trainer.
During the spin itself the speed is low and the wing is stalled so it's relatively low stress and airframe age is irrelevant; if the recovery is mishandled then I guess the stresses may rise at that point.
Just out of interest, why did your instructor ask you to look at the back end of a Traumahawk during the spin?
HFD