Whenever isn't recurring

Since moving to St. Louis, I've noticed people using the word "whenever" to mean a specific instance. For example, "I saw him whenever I went to the library," could refer to seeing a friend during one specific trip to the library, rather than seeing him at every trip to the library. At first I thought that it meant they couldn't remember when they went to the library, but that doesn't necessarily seem to be true. Is anyone familiar of this use of "whenever" to mean "when"?