Being one step removed from the hiring manager at work, the one thing I have noticed about some older candidates is sometimes their background/resume/performance demonstrates to me that some just don't show an aptitude for learning quickly in technical problem spaces. Personally, I don't particularly care about how old someone is, but I absolutely need to see the ability to learn (in addition to the standard things of integrity, good problem solving ability, is not a jerk, etc.). My company even trends older than a lot in our industry (I might be average at 32 here), especially for a smaller one.