What was that about?

As I was getting dressed this morning, I happened to glance at a grade school picture of my oldest child, Sara. Instead of the happy nostalgic feeling one often gets when viewing old photos,I immediately became overwhelmed by a wave of sadness.My thoughts turned to days that are gone and I will never have again. I became overwhelmed with a grief for what I missed and will never have again.I could not break my gaze and the longer I looked at it the sadder I became.In a few short moments, the pain became unbearable. I physically had to turn away to pull myself together.
This was uncharacteristic of how I normally feel when looking at old photos.I have no idea why I had this reaction today. No one is ill, or in trouble or estranged from me. 
I just became sad!
I finished dressing and fled from my room as quickly as possible.
The rest of the day was absolutely fantastic.I got a lot accomplished. I had a great workout. I made a terrific dinner.Yet I was haunted by the memory of how I felt looking at that picture. Interestingly, Sara called at one point today just to chat. I was busy and asked her if I could call her back. On my way into my workout, I took a second and called her back before she went out to a class this evening.
We made a date to catch up tomorrow.It will be high on priority list ,that I can promise.
So I am left wondering,was this a moment that came and passed? Or is there something going on that I might want to pay attention to? And do I have the strength to allow myself to face the fears of the sadness I felt and go there anyway?
It's daunting, that much I can tell you.
I can also tell you that I have not been able to come to a decision on this. I am sure at some point in time, I will muster the fortitude to examine this and peel  the onion .I am not sre when that will happen. I promise to let you know when I do!