Hey Stevenq, these sorts of lite emails can morph into a recycle, if you are willing to take on 99% of the relationship again. If you were to answer with a big ol' explanation, it could lead to more talking or she might drop it cold. It depends on her mood in the moment.
I do respond to ex's emails, mainly because I am strong enough to not go down the recycle road and well, I worry about that he is an unstable person, no response might be upsetting to him. Can't help it, I still care about his well being.
I respond and pretend I'm talking to my brother because I don't have any high emotion talking to him. "Oh that's right, thanks for letting me know. Take care, stevenq." A nonreactive response, no JADE. Justifying, apologizing, defending or explaining.
Ex rarely responds to my responses, I don't give him anything to 'go on'. I don't risk my feelings of putting them out there for him to embrace or stomp on.
Just another option for you to consider.