It's a long time since I ventured in this section, so deep breath...
I have been friends with a neighbour of mine since our children were about a year old; they are now 7. Her boy gets on well with my two dds, although they bicker like siblings/cousins because they know each other so well.
We tend to spend at least one afternoon a week together. In the holidays, I take her boy out for the day at least once, then we go to hers for tea.
Although with his parents his behaviour can be a little challenging, his behaviour with me is generally very good. However, the last couple of times that I have taken him out, he has been fine all day and then started complaining when he gets home. e.g. I took him to see The Princess and the Frog and treated him to sweets etc then when he arrived home he said he hated it, that it was a PG (it wasn't) and that he had been very very scared (he hadn't) and that it was a stupid girls' film 
Today I had organised a music workshop with songs and dances and crafts and spent quite a bit of time getting it ready. I took him this morning, he enjoyed the workshop (lots of people there that he knew) - it was about 50/50 boys and girls. I then took him for lunch (which he enjoyed) and then to my house for a play and to watch a movie. I took him home about five.
When his mum asked if he had enjoyed himself he said no, it had been boring and he hadn't liked it, and he told me that he had only agreed to go because then he could get a sticker for his star chart for Christmas 

I have to admit that I was hurt and upset about this. I laughed it off, though. His parents were a little embarrassed but tried to brush it off, saying well I am sure that he enjoyed it really.
The more I think about it, the more annoyed I get tbh. I have invited him here for a Halloween party on Sunday, and I am dreading if he says something rude then, I might get REALLY annoyed.
AIBU to be annoyed about this? Should I have said something to him, do you think?