The first time I remember coming across it was when I read Dumbledore's line, "Alas, earwax", in Harry Potter and the Philosopher's Stone. I loved the way it sounded, and how it comes across as oldy-worldy professional with a tone of amusement, like when we were kids and we had a phase of using 'thee', 'thou', and Shakespeare-ising everything. 'Hadst thou completeth thy homework?' It crept into my conversation and writing, text messages especially, and it seems to have become a permanent fixture in my vocabulary. I admit, I hadn't really noticed, until I got a reply by text that said words to the effect of 'you're the only person I know that uses alas in everyday conversation. Love it.'
Yeah, so do I :)