I think you should say something, just to let the teacher know that you are one of the 'interested' parents, who is willing to work with your child.
I so wish we had said something back in Reception when our dd didn't progress one iota, only to be told in Yr 1, that she had problems with her reading and the whole class were basically behind their targets, ('but don't worry the Yr 1 teacher is very good and will bring them up to the right level').
Yes they have almost caught up, with this brilliant teacher, and dd had extra reading with a specialist, but going into Yr 2, her writing is worse than when she stated in Yr 1 and I was doing a lot of work at home with her on it - but I know that poor Yr 1 teacher couldn't do it all!!
We took the hard decision last week, to move her to a private school, starting Monday. Luckily we can just about afford it, as only have the one child.
Yesterday, dd told me she had done some reading with one of the TA's, when she told me the book, it was one she had had back at Easter with her specialist reading teacher and when she told the TA this, their reply was 'well then you will be able to read it then'. Which my dd proudly told me she did without one mistake - and she did the voices!!!. She is still on two levels below of what she was reading with the specialist and reads at home, but they seem to be unable to progress her up!
If I had expressed my concerns back in Reception, we wouldn't be at this stage now. The head actually apologised to me for the standard of teaching they receieved in Reception, saying it was a Newly Qualified Teacher, who probably didn't have the confidence to do a little more with the children and how she (the head), wish she had stepped in sooner. I am grateful for her honesty and the apology, but it made me realise the impact of one 'poor' teacher.
Learn from our experience, go with your gut feel and mention it now, don't wait, and if you are still not happy at half term, take it a little further up the line and express your worries.