[w00t]

Not only can I not find any mention of anything to the effect of "Don't admit to using Tor" anywhere in the docs, Tor would be very shitty if it relied on people not knowing you used it, as that is almost exactly the definition of security through obscurity.

As for your later statement, if I have the resources to even attempt to track you through Tor, I definitely have the resources to know that you're using Tor without you explicitly saying so. It's blatantly obvious that someone is using Tor when a bunch of encrypted 512-byte packets are getting sent back and forth.