My 10-year-old son took a field trip last week to outdoor school, a three-day extravaganza of river exploring, soil examining, flower dissecting, wildlife watching and learning camp songs that make me smile with delight whenever I hear him sing them.

But this column isn’t about what he learned or did at outdoor school (although I should dedicate an entire column to what a saint his teacher is for shepherding some 30 10-year-olds through three days of bus rides, mess hall, cabin sleeping, nature walks and group activities. Seriously, he is a brave man with the patience of Job.)

No, as much fun as outdoor school was for my son and his classmates, this column is really about what happened before Harry left on his trip.

He packed all his stuff. I made him double and triple check that it was all there. We went over the list one last time then loaded his stuff in the car.

Pulling up at the school, we saw the big charter bus parked out front and a bunch of students and parents milling around. Harry hopped out and lugged his duffel bag to the bus. He chatted with friends. Me and a couple other moms stood around like accessories, wondering if there were any last-minute mom jobs to be taken care of. Reminders about coats and shoes and hats shot out into the morning air and landed on approximately zero 10-year-old ears.

I had to physically turn my son around to get his attention for long enough to say goodbye. “Goodbye,” I said, holding out my arms for the expected hug. “Have a great time. I’ll miss you.”

“Bye, Mom,” he said. “I will.”

And then he patted my arm. No hug, no kiss on the cheek. Just a few pats of his hand on my upper arm, and a smile that was meant to be kind, but bordered on patronizing.

Oh. I get it, I thought as Harry boarded the bus without so much as another glance in my direction. He’s done with me.

On the cusp of middle school, at a point when peer relationships are becoming more important than parental relationships, my son doesn’t need me any more. At least, not where his friends can see.

I knew this day would come. I’d heard parents of older children talk about it — about how their kids reached a certain age when they were embarrassed to be with their parents and public displays of affection from Mom elicited more eye rolls than reciprocal hugs.

But I guess I thought we were still a few years away from that. I thought it would come with teenage angst and the agony of trying to fit in somewhere in high school. I thought it would be a slow transition from daily hugs and kisses to the arms-length assertion of his independence.

Instead, it was a sudden pat on the arm when I expected a hug. It was the slight condescending tone of voice when he said “I love you too, Mom.”

I suppose I want my sons to need me less and less. I’d like for them to move out of the house eventually and be able to function on their own. After all, part of the measure of my success as a parent is going to be whether my kids can live fulfilled and healthy lives on their own. In order for that to happen, they need to learn a certain amount of physical, emotional and (please?) financial self-sufficiency.

But does it have to start at age 10? He may be ready, but am I?

Harry returned from camp a few days later and I had to remind him to give me a homecoming hug, but he squeezed pretty tight when I got it.

And the other night, when we were working together on the computer, he quietly leaned over and kissed my shoulder, for no apparent reason.

If this is the level of quiet, subtle affection I get from him now, so be it. Even if he doesn’t need it any more, I do.