We could rather ask if there are any examples of a ship producing such a signature while not
at warp. Supposedly, starships can "run silent" by shutting down some of their systems; this wouldn't work too well if warp drive couldn't be made silent for periods of inactivity, but needed to be dismantled or something...
I guess it can go either way. In "The Sound of Her Voice", the mere presence of a warp core made transit through that weird atmospheric chrono-haze dangerous, not the actual use of warp. But "Sacrifice of Angels" is our only example of warp signatures within the wormhole. And in nice contrast, "Playing God" shows a runabout traversing the entire length of the wormhole at crawling speed; actually using warp drive within should thus get you across the distance in a millisecond.