You need to drive it a little more to see what happens, it could be a small piece of trash got in the way and when you stuck your foot in it the line pressure went high enough to make it break free.
In the early 70s I worked for a company that was still using 2 old gas powered White dump trucks like this one. I got them yo buy a IH diesel for me and would make 1.5 trips for every 1 the Whites would make. 🤣
It got my curiosity up and I did some looking and found that they had developed this 525 hp version.
Into this 700 hp beast before EPA regulations and GM killed it.