Whenever I leave my office building for lunch a guard in charge greets me (everyone) with a:
Edit: This is a recording of what I heard. Based on comments I received under this question and what I set my ears to hear, I do hear either いらっしゃいませ or いってらっしゃいませ when playing back.
I am used to hearing the phrase いらっしゃいませ for "welcome" (explained to come from 居る "be" or or 来る "come"), but in this case I am leaving, it's not my destination and I won't spend more than a second hanging around the guard.
Why isn't it odd? If it's indeed いらっしゃいませ what image should I create in my mind when told so? Me coming to the guard's place, me leaving the building, me being, me leaving and coming back?