The lentils in the above photo are raw. They did not form a solid block when they were dry, but after I poured a bit of water in, they suddenly did this.
Obviously, they need a bit of washing. Red lentils stick to the pan easily.
Red lentils have no skin and are thus more absorbent. They literally sucked up the wee bit of water clinging to them along with their neighbors. Surface tension of the water couldn't be broken by the light-weight pulses.
When crumbled apart, the brick doesn't feel pasty, no?
Next time maybe pour lentils into water; either way, no harm to finished dish.
If they got wet, and were not washed, they likely had some kind of starch on them that turned to paste, thus binding those little guys into a brick.