As I do this myself it would not bother me.
I help in DD's school 2 days a week (did one day a week last year) and someimes 3. I am a qualified teacher (although secondary) and I am considering becoming a TA at primary level. I don't want to teach anymore due to the stresses and worklad. Being in school so much, int he 3 infant classes, is excellent experience for me.
I believe I am very professional at work, and although I do spend a lot of time in DD's class, when in class I treat her the same as every other child, despite her calling me mummy and her closer friends calling me by my first name.
I am also pretty well qualified for the role, even if not paid, IMO and certainly in the eyes of the teachers I work alongside.
Fortunately no parents in the 3 classes I help in seem to object to me being there.