I see why you're confused Kia I would have said they were personal space issues - how close you stand to someone or if you feel like communicating or not if you pick up a book and start reading when sitting with someone and if you walk off when someone is talking to you I would have said that was a manners issue - guess I'm wrong on all counts! Maybe thats why I am so crap at it!
Humour is a funny thing (no pun intended!) I often use humour to get people to back off - for example people were going for a night out at work and they asked if I wanted to go - and I said sorry getting my cats claws painted

they just laughed and I didnt have to say - sorry cant be in a group of more than a few people or i get panicky and want to run away - so I guess your T may have a point - having said that you know you're mum better than they do and you know when she is joking or not.
Take Care P7