Recency illusion

The recency illusion is the belief or impression, on the part of someone who has only recently become aware of a long-established phenomenon, that the phenomenon itself must be of recent origin. The term was coined by Arnold Zwicky, a linguist at Stanford University who is primarily interested in examples involving words, meanings, phrases, and grammatical constructions. However, use of the term is not restricted to linguistic phenomena: Zwicky has defined it simply as, "the belief that things you have noticed only recently are in fact recent".

According to Zwicky, the illusion is caused by selective attention.

Examples
Linguistic items prone to the recency illusion include:
 * "Singular they": the use of "they," "them," or "their" to reference a singular antecedent without specific gender, as in "If George or Sally come by, give them the package." Although this usage is often cited as a modern invention, it is quite old, going back to the 14th century.
 * The phrase "between you and I" (rather than "between you and me"), often viewed today as a hypercorrection, which could also be found occasionally in Early Modern English.
 * The intensifier "really," as in "it was a really wonderful experience," and the moderating adverb "pretty," as in "it was a pretty exciting experience." Many people have the impression that these usages are somewhat slang-like, and have developed relatively recently. They go back to at least the 18th century, and are commonly found in the works and letters of such writers as Benjamin Franklin.
 * "Literally" being used figuratively as an intensifier is often viewed as a recent change, but in fact usage dates back to the 1760s.
 * "Aks" as a production of African American English only. Use of "aks" in place of "ask" dates back to the works of Chaucer in Middle English, though typically in this context spelled "ax".