I'm pretty sure Morrison said Bruce was 39, in the lead-in to RIP. I'll see if I can dig up the cite and confirm my memory (my google-fu is, as of yet, too weak to turn it - or one confirming you memory - up). I remember the fact that it confirmed he was pushing 40 really pleased me.
That aside, I agree with the substance of your post. Ageing is screwy as hell - I think the original Titans have hit the point their going to be frozen at forevermore (mid-20s)- they might age, except that would force moving the Trinity's generation up into their 40s or even their 50s - and we seem to be seeing part of the next generation down being actively deaged to keep them back from there. And then the kids (as in kids, not the youngest heroes) are all over the map...