Does anyone elses dogs do this?

i have an 11yr old terrier and her 8yr old son i have had her son all his life and just got her a few weeks ago. about 10min ago my 8yr old got up he was sitting on the couch anyways he got up to jump down she sat up she too was on couch and went over by him never growled or anything but he freaked out every place he turned she was there in his face he looked a litttle like oh my and i was just wondering if anyone else had dogs do this and why do you think they do it?