"Inaudible Melodies"

So, I'm currently sitting in the library listening to my headphones while writing a post for class tomorrow. Suddenly, I think to myself, "Have I been singing outloud without realizing it?!?!" (It's quite possible - Death Cab for Cutie is that good.) I'm pretty sure that I haven't hummed along or sung random snippets of lyrics... but how can I know? I just can't remember... and it's bugging me.

It would be different if everyone could hear the music - then you just blend into the background noise (hopefully). But in the quiet of the library?! That would explain the sideways glances, or am I just imagining those, too? I'm almost embarassed - I'm nearly blushing just thinking about the possibilities. Now I'm wondering if I'm the only person who blushes thinking about embarassing things she might have done without realizing it.