I'm 42 and the only problem I had about age vs experience was with First Choice. I had 800hrs 757. Nothing mentioned but heard a few things afterwards. They had a stiffy for 22yr old girls and boys at the time I remember.
Looking back now I thank god they were sniffy about it. All silly really because you've got a good few years of flying left even at 40 and less likely to run off to BA to wear a silly hat.