cornish x (I think) stopped laying - any idea why?

Lucille, whom I suspect is a cornish cross, has been laying reliably every other day since late June. Now it's been 4-5 days without an egg. I know she's not considered a laying breed, but does anyone know why she might have stopped laying? As far as I can tell, there hasn't been anything traumatic going on, and she doesn't seem sick or unhappy. Is it the heat? It's been pretty freakin' hot here in GA (97 degrees this afternoon) and I know meat birds have a difficult time in the heat. I'm keeping a close eye on her and she has plenty of shade and water.

I got Lucille from a neighbor so I am not 100% sure of her age or breed, but she's around 8-10 months old and a really hefty girl:

 

thanks arlee453. I honestly never thought she'd live this long. Lucille is primarily free-range, so she's pretty active for a bird of this size, and one of my 4-month-old cockerels tries to mount her every day -- but I'm not sure if that helps or not! He's half her size and it doesn't seem to bother her. I was really surprised when she started laying, so I consider every egg a bonus -- just wanted to make sure not-laying isn't a symptom of something bad.