Hi NYG, in your sitch I think it is good for you to be relatively dim contact-wise. I also favour the do not respond option. After all, if it was something important, she would have left a message.
If you do want to contact her, I would go with something like - hey, noticed I missed a call from you yesterday. I'm around today (but have plans this evening) if you need to get in touch :-)
I think this satisfies your need to respond, keeps it light and let's her know you have a life. Then, just leave it and if she needs to get in touch she will.
Take care & have a good weekend :-)
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus