Input meter showing audio (or midi) coming in even when there is no sound or keys played

This just started happening but I don't know exactly when. Perhaps when I installed X1C? In my project, I have inserted the SI Sting Session soft synth. While I am not playing any keys, the input meter is bouncing up and down as if there are keys being played. There is no sound. When I play some keys, I get sound. Any ideas as to why? Thanks --Edit-- Too bad you can't delete a post :-( I figured it out. I inserted another synth (TTS-1) and it did not have the problem, however, there was a lot of vibrato on the piano sound. I wiggled the vibrato controller on my keyboard and guess what? The input stopped bouncing up and down. Apparently the keyboard was sending vibrato messages. I don't understand why there was no vibrato on the sound for SI Strings but there was on TTS-1 (even though the input meter was silent).