Asked a strange question at work

So I found this internally quite funny but my mum is very unhappy with a comment my manager made to me at work and now I need some opinions. I have done 5-6 shifts at the pub I work at, and on my last shift the manager sent me home early due to my performance and called for a probationary period meeting about how to move forward constructively. Now I understand his perception of my performance has lead to this meeting but that's not really what the concern is, and also any other employee would be slightly confused as to why the meeting is happening because I am always trying my best and contributing as much as I can, putting on a friendly face as I do so and so on. During the meeting I explained my side that because I had done 1 shift with him since I started and it wasn't an accurate representation of my performance and improvement from the last, as we have had family issues which I had been dealing with all night before my shift and my head wasn't in it to be totally honest. I also prefaced this with 'I hate making excuses but to explain my situation'. He then proceeded to ask me if I had a learning disability which I hadn't made them aware of, immediately after. He had also told me within the 5 minutes prior that he wouldn't trust me on the bar by myself on a Monday afternoon if there were 3 people in there. Now I do not have any learning disabilities which I am aware of (there is nothing wrong with having one at all of course), as my maths degree and 3 A*s at A levels may show. Whether I do or not isn't the question, but how is a comment like this generally viewed? For reference he is the general manager and it is my first month of employment working, and my first time working part time on bar as my primary role. This whole meeting was also ON THE RECORD with a third party witness