I suppose you could be identified as "overqualified" if you don't limit entries on your resume. Actually asking for an age or birthdate is illegal in the U.S.
At my previous company, where I began in the startup stage, we had lots of people older than 40 and 50 in IT. We had a QA guy who had to be at least 60. I suppose it all depends on the company (and probably the geographic subculture) but this "ageism" stuff is out of my experience -- I'll hire someone who knows what he's doing and is motivated to do it, period. Stupid shit like "but he has a wrinkle" is moot.
Ageism in IT is very real. This is just one of the mechanisms by which it operates. The other side is the (youngest) programmers who haven't yet grown out of language fanboyism and dismiss your experience of last year's technology as irrelevant. Fortunately they're rarely in positions of hiring authority.
The IT industry takes about 10 years to cycle through fads. Someone I consider experienced has been through at least one cycle. I want people who can say XML? Oh yes, well I've never used XML but in the 90s I was doing EDI... (insert tech of choice)