1. You’ve started referring to apps by their abbreviations instead of their actual names
2. You’re seriously considering installing an applescript-controlled x10 system in your home just so Quicksilver can actually make you coffee in the morning
3. You’ve changed the keystroke to Cmd-Space instead of Ctrl-Space just so it’s that little bit closer.
4. Your hands twitch in the junkie Ctrl-Space gesture whenever you’re looking for something in a shop, library, or similar public place.
5. You’ve actually written long, exhaustive articles on the pros and cons of different quicksilver interfaces

Of course, this whole post is entirely facetious as it’s impossible to use Quicksilver too much.