If it was me, I wouldn't call her to let her know how A is doing. I dare say she will ring sometime during the day (or text, or email) to ask how he is. Particularly if he seems to be fine. I think it would be a bit different if he was still sick. You are the parent today, your w needs to work. Let her concentrate on that. She will appreciate you being a dad and being someone that she doesn't have to check up on (I know, I know...she hasn't acted like that much...but I live in hope for the future). You will reap the benefits at some point (cross fingers).
As far as A not seeming sick. That's definitely a kid thing. d7 doesn't often throw up, but when she has, she has been fine ten minutes afterwards (sometimes even fine straight away - particularly when she was A's age). It's only been as she has gotten older (5 years plus I guess) that throwing up usually results in her sleeping more from the effort.
** Purple
As soon as you trust yourself you will know how to live. Goethe
