Sunday Soliloquy - Am I in Mid-life Now?

Am I officially in mid-life now?

Evidence For:

1. This week I received an email inviting me to my high school reunion.  I had to go back and check the records twice, it couldn't have been 20 years since I graduated from high school?
2. I have a kid that is choosing which high school she is going to next year (and have been married for 13 years).
3. I then looked in the mirror and of what hair is left, most of it is now gray.  
4. My back is constantly sore and I am starting to feel arthritis in my hands (especially when it is cold and damp).
5. I used the phrase 'when I was sitting in your seat' in class last week to talk about paper ticketing versus online sales.
6. It is harder to keep my waist reduced even though my appetite is shrinking.

Evidence Against:

1. I had a child that turned one yesterday and another who is five - so they are still little.
2. I haven't turned 40 quite yet.
3. I can still run and beat the children at almost everything.  Though they can outlast me at times.
4. I feel young...

Did I slip into mid-life and didn't get the memo or is this just my shot across the bow reminding me it is coming in the next few years?