I readjusted the valves and loosened them up compared to where I had previously adjusted them. I know for sure they are not too tight right now, unless they tightned up when driving? Is that possible?

52 Chevy 3100 5 Window, LS Swap, 4spd Auto, Vintage Air AC / Heat, CPP Power Front Disc Brake Conversion with bearing upgrade, Power Steering Conversion, LED Tail Lights