Yes, it happens to many pilgrims (including me) but I am sure not to all. I suggest there is likely a direct correlation between the amount of "life experience" you have when you walk the Camino (aka "age"), and the concomitantly greater burdens / baggage of all those years you carry with you.
We, all of us, simply pick up more emotional "stuff" or baggage as we progress through life. More experiences, joy, memories, sorrows, suffering, and loss. Many of these burdens can be very deeply hidden. The longer you are around, the more of these burdens you acquire and carry along "on your back" or in your heart.
All of us vary to the degree we can carry these accumulated burdens until they erupt as tears. Every person is different. Most of us in western cultures are taught from childhood either not to cry, or to "suck it up" and soldier on. I know I was.
The baggage you carry can be something as common as a difficult childhood, parental divorce, losing family, friends, or colleagues at any time over your life. Also, for some it can be repressed and deeply carried past traumatic events. The overwhelming beauty, serenity, and peace of the Camino forces the deep feelings to the surface. This need not be post traumatic stress disorder caused by warfare or violence. It can be left-over negative feelings from failed relationships, marriages, jobs, etc.
Walking the Camino exposes us to the other side of life; the immense beauty, an overwhelming sense of history, serenity, order and peace. Physical challenges aside, simply being amongst all these calming influences can cause any number of these repressed memories or feelings to bubble to the surface at any time, and with sometimes oblique, vague, or indirect reasons. The Camino DOES heal!
Last year, I had the privilege of spending nearly a week with the Rev. Philip Wren (aka, MethodistPilgrim98). We walked together from Orisson until we parted ways at Logrono. He passed away from complications of his type I diabetes later, while asleep that evening in the municipal albergue.
As we walked together, Phil was intent on using his digital SLR camera to capture iconic images of the Camino. He also used the video functionality to try to capture the "sound of The Creator." To Phil, this was the sound that the wind made as is passed through the late winter wheat in the fields to either side of the Camino path west of Puenta la Reina. As a frequent guest speaker on behalf of the Confraternity of St. James in London, Phil wanted to be able to show his audiences the presence of The Creator in nature.
I helped him hold his bright orange poncho out of the way so it would not catch the wind and make snapping noises. But, I remained completely silent as he recorded several times. These were profound silences. It was a beautiful, sunny day, and the wind was cooperative. Phil believed that he sound of the wind through the wheat was the sound of his God. Who was I to judge? But, I shared his wonder and excitement at these moments. It colored the remainder of my Camino.
After we parted ways at Logrono wishing each other "Buen Camino" and "Vaya con Dios," I reflected on these moments. It was not until about a week later that I first heard of Phil's untimely passing at "cafe coffee" one morning coming out of Burgos. As I started walking again, I had difficulty seeing through MY tears. The shared experience we had earlier, combined with my personal sorrow, and overall sense of loss of such a kind soul to the larger Camino Family caused me to blubber like a baby. Fortunately, or not, I happened to be walking solo at the time. The wind dried matters up and the somber day continued...these were not the last tears I shed along The Way.
It happens sooner or later to most of us... and is certainly nothing to be ashamed of or guilty about.
Celebrate life!
