Yup! Gerry Conway, scribe of the awesome Silver-Age Spider-Man was nice enough to read my theory and respond with his own take:
Thanks, Adam -- a no-prize for you. I'm of the opinion that some fans (like those who believed this was a plot hole) try too hard to apply real-world logic and assumptions to fantasy-world situations. But to respond in kind, my attitude toward this would have been, Peter's spider-sense isn't a fine-tuned, mechanical sonar/radar piece of technology: it's an organic, instinctive response to perceived threat -- real or imagined. Like our own fight-or-flight response, it can be activated by perfectly innocent stimuli, because it's an instinct, not a calibrated, 100% accurate-all-the-time weapons system. (As if weapons systems were 100% accurate all the time.) The fact is, someone was in Peter's apartment when he didn't expect anyone to be there -- that would be enough to get *my* spider-sense tingling. It's called being surprised. That's about all the logic and rationalization it needs. (But I do like your rationalization too.)
Of course, my own rationalization was that Pete's secret ID was in danger of being discovered by a Mary Jane snooping around uninvited in his apartment, which ties into Gerry's take.
Isn't it awesome that some comic writers are willing to share their thoughts with us? I am truly not worthy!
Thanks so much, Gerry! It was a real treat to hear from you!