Its not really controversial per-say but...

This didn't fit any other group and I guess it could be considered controversial. Anyways, I provide in home therapy to children and today the mother left for an appointment. My phone was almost dead and I saw her charger plugged in on the counter. Of course being the phone addict I am, it was calling my name. But I felt weird using it and I felt that would be an inappropriate question to ask if I called her and interuppted what she was doing. Please note, I use my phone for several of his programs and although it's not a "need" it does assist me in his therapy. I plugged it in for a few minutes but I got panicky that she would come home and see it. My boyfriend said he doesn't see the slightest bit of a problem with it. After all, it's just a charger. That's what it's there for. So my question is...would you be rubbed the wrong way if someone used your non-personal items while in your home without asking?