They would appear if your analysis is not complete. You can turn off the banner in the UI for the effect.
It is also almost always a good practice to use only the footage you are processing with warp stabilize in a comp, only run warp stabilize, then render a digital intermediate using a suitable visually lossless production codec so you can use that footage in another composition.
If you are compositing something in footage that is warp stabilized, like replacing something in the shot, then it's a good idea to NOT run warp stabilizer on the footage, but instead nest the composite with the tracked composite in a new comp and run Warp Stabilizer on the nested comp instead of the footage. Warp stabilizer is a CPU and system hog, the results bloat your project size, if you run out of cache there can be problems and it's generally finicky. If a shot is longer than 2 or 3 seconds I always create a DI and replace it in the production. I seldom if ever save a project that has a warp stabilized layer included in the project because it's just not reliable.