What made these red lentils 'brick' together?
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.