I haven't found that, or anything even close to that, to be the case at all. Maybe it's a geographical thing? I'm on the East Coast and from what I can see, if you have a "hot" skillset (Hadoop/Big-Data, MongoDB, Clojure, Node.js, Angular/Ember, etc.) you won't have any problem finding a job, regardless of your age.
Personally, I'm 41 with 15+ years of IT experience and I have never felt any sense of age discrimination at all. But, I'm also constantly working to keep my skills current, and I do a lot of things to make myself attractive and known in my area - speaking at events, writing articles, blogging, etc. shrug
My feeling is, if you're sitting at 15 years of experience and you've been, for example, writing Java code for 15 years, go pick up a Scala or Clojure book, or learn R or take the time to learn Hadoop, Spark, Storm, Kafka, MongoDB, etc. If you have skills that are "hip" at a moment in time, I don't think it's usually going to matter much how old you are.
OTOH, if you are a 15 year Java programmer who is still writing Java 1.2 code for a JSP based app that integrates with a COBOL book-keeping system on an IBM S/360, and you refuse to even look at that "new fangled" Java 1.3 or newer, then yeah, you might find yourself in a tough spot if/when they decide to turn off that mainframe.