It looks like what I'd say has already been said in the thread, but yeah.
You're probably not used to having to just trash/move on from whatever you've done, for the sake of practice, and you took a genuine mistake as something with more intent behind it than it had.
And you shouldn't even be drawing at work.
But if you are, at least close your fucking sketchbook, first. I take it you work in an office, so of course people will make mistakes like that, since there's paper everywhere.
And like fuck some normie is going to be able to tell the difference between a sheet of Strathmore and copy paper from Staples.