I can't find any examples using google and I feel like its pretty blatant age discrimination so it must have been challenged at some point. Hopefully this is the correct sub for this question.
The age requirements for federal candidacy are written into the US Constitution, specifically Article II, Section 1, Clause 5 for the president, and Article I for senators and representatives. Because the Constitution is the highest law of the land, there's really no challenging something that's written in plain language right there. So while it is age discrimination, it's constitutionally-permitted (constitutionally-required) age discrimination. The Constitution trumps anything else.
Source: United States Constitution
As Senorjefe noted, it obviously couldn't be challenged on legal grounds, but it is certainly debatable whether or not the age requirements constitute good governance.
Has there ever been any substantial movement to amend the age requirements set forth in the Constitution? I suspect the answer to be "no," but something more evidence-based would be nice.