This sounds basically identical to what we were going through with our barred rock. I will say that she's still off and on got some weird stuff happening with her eggs (almost every egg is a double yolker except for maybe one or two). Occasionally we will still get a random soft shelled egg or two overnight and a slab sided egg also later in the day. Overall though we haven't noticed any lethargy again so as long as she's passing the eggs, eating, drinking and acting normal we're just leaving her be to get herself sorted out.
We did figure out shortly after this thread that my pullets weren't eating the new layer food we had switched them to and we attributed that to our 'flock' egg problem. Since we switched the food back to Layena Pearls they have been eating more and we've been seeing less egg issues.
From everything I've read and heard it can take a month or two for them to work out these weird reproductive quirks. If yours only laid her first one on the 4th I would try not to worry too much. We have one that's been laying since March 18th and she still has the occasional hiccup. 
