I see this quite often in the shop.
Most often, with schrader valves, the stem is torn out because the tire is riden at a low air pressure.
Less frequently, threaded presta valves are damaged during normal deflation because the nut is too tight.
Occasionally, there is some other cause like an unusually sharp edge at the valve hole etc.
Hope you figure it out.
My numbers above came from the usual am ride with no real time limit. There was alllways a litle threat of rain. Five of us started out. Before we were 5 miles into our loop around Drs Lake, one guy was already talking about turning back just because it looked like rain ahead. I talked to 2 others and asked if they wanted to go a little longer and one asked if we could hit the dirt road. I said sure. We went on while the boss and "da otder guy" went back to the shop.
The three of us headed down 17 and made our turn around and headed towards the "Old Hard Road," a .75 mile stretch of dirt road that was being graded when we got there. It was soft and deep and not even my 25s were wide enough to float across the top. The least experienced guy with us spun out and bogged down in front of me. Then he just kinda fell over. we all just sorta laughed and kept going.