I have a year old RIR that has been dropping an egg almost nightly while she roosts. The shell is quite soft when she does it. I have separated her from the other 3 girls and both nights she didn't lay the nightly egg, but as soon as I put her back with the others it started up again. She seems healthy, active and is eating well. I save all my egg shells, grind them up very fine and add them back to their food almost daily. I also offer them free choice oyster shells. I am at a loss with what is going on here. Could it be that she is starting to molt? I have 4 RIR and used to get 4 eggs daily but now I am down to 1 or two, then add the dropped one at night. Anybody else have this happen to them???