Is it me?

I don't know if anyone else ever feels this way, but a lot of times, when something happens (I'm talking about interpersonal relationships of all kinds), I immediately assume that I said/did something that made the other person upset with me and that's why there is limited or no contact. For example, these last few days, I was trying to contact a friend of mine and she didn't call me back. In my head, I knew that she is busy, tired, or whatever, but in the back of my brain this annoying little nagging voice piped up: YOU must have said something to offend her. You probably shouldn't have said (whatever it is that I said last time we met that was slightly maybe could be construed as offensive by someone who is completely hyper-sensitive, which none of my friends are). The voice is completely irrational and sometimes just plain stupid, but if I let it (and before therapy, I used to let it), it takes over the entire head and I obsess about it for days... This time, I tried to stomp the stupid little nag down, and it mostly did stay down, and then this morning, we exchanged emails with my friend, and as usual, it had NOTHING, absolutely nothing to do with anything I said or did, she was really just tired and busy and slightly depressed and didn't feel like talking to people. Totally understandable, and the normal, rational part of me knew that... I can't believe how much hard work it's taking to stomp that little nag down though... hopefully it will get easier with practice. I even visualized this whiny, nagging little thing popping up and me bonking it on the head to make it disappear. LOL.