1. She's new at it & is not yet 'regulated.'
2. Anything changed since she laid the 1st egg--new dog, new chicks, move coop, etc? Some chicks can take time to adapt to change.
3. Check her for lice/worms?
That's about all I can think of right now, although there is a handy little 'sticky' at the top of this section's page...I just forgot to go there first to copy the link.
FWIW--My oldest EE started laying in July, also STOPPED laying in July...no biggie 'cause I did some re-arranging & cell assignments...she just started laying again on Labor Day!