I hooked up with a girl a few months back. I had fun, but I assumed we'd never see each other again, so didn't respond to her text the next day. Well, turns out I did run into her, and she was miffed that I never texted her back. Was I being rude here or was she being too sensitive?
Well, a little of both. In not texting back, you were, in fact, communicating that you didn't want to communicate with her anymore. That's within your rights as a modern day hookup collaborator. However, a little extra courtesy padding should be applied when dealing with people we've seen naked. She was probably operating under different expectations than the ones you were, which is to say, maybe she thought you would see each other again. Maybe you thought "casual sex" and she thought "rapidly encroaching belief that I am going to die alone." Maybe she just wanted to ensure that your walk of shame the next morning didn't result in you being stabbed. Who knows? Unless you explicitly said something like, "That was fun! What's even more fun, though, is knowing we'll never see each other again!" It's not out of the question to assume a night of fluid exchange might lead to other kinds of exchanges, sexual or otherwise.
It also depends on what her text was. If it was something like, "Hey, I left my 4-inch bitch heels at your house. Whence-forth can I retrieve them?" And you didn't respond, that's rude. If it was something like, "Hey, I'm so glad we could engage in floor coitus" or something, that's a bit more wishy-washy, but also something that you could easily respond to in a few seconds. If it was a text situation where replying seemed redundant, then you're free to ignore it.
As the Chairman of the Committee Against Gratuitous Texts, I'll admit I'm guilty of not responding to texts, like, all the time. I feel that my nonresponses are just as effective as saying "no," but not everyone feels the same way, especially my mother, who just learned how to text and thus considers ignored texts to be synonymous with irreparable scorn. I'm also apparently living in the textual Stone Age where I get only 200 texts per month, which I frequently exceed, despite my draconian anti-response measures. Trying to explain this to a hookup would be ridiculous, so I often just opt for seeming jerkish. Feel free to emulate this wildly effective strategy.
If you are called out for not texting back in the future, I've found a simple, "Sorry, I'm not a big texter" usually does the trick just fine. No harm, no foul. Seriously though, I want my heels back.
Social-media mistress Anna Pulley likes to give advice about how to play well with others on the internets. If you have a question about etiquette involving technology, shoot her a question at AskAnnaSF@gmail.com.