My mum thinks my husband was being disrespectful

Me and my husband are currently visiting my family in the UK. My mum doesn't like my husband and has never liked him. She also finds some of his tics annoying. He has autism and sometimes hand flaps when he gets excited. I came back to her home after being out all day with my dad and my mum was stuck with my husband and he made a little hand flap because he was excited to see me. She thought that was silly and dumb. Here's why she's mad. She took us to this place that makes really good hot chocolate but they put melted chocolate on the outside of the cup too. I don't get it. When my husband got his he made a weird sound. I asked was he ok. He said "uhuh". He didn't want to touch the cup. Sensory issues. Bad sensory. My mum said he's a big boy he'll be fine. My hubby would not touch the cup so I asked for one without the chocolate on the outside. They gave us a new cup and I poured his drink into it and that was that. My mum got so mad and said my husband is being disrespectful and that it was rude. I don't get why she's so angry and she's being even more rude now.