You need to keep an eye on this one. If she's not broody, and it doesn't sound like she is, she could be having a problem passing her egg.
 
I have a couple such hens. They will spend hours on the nest without producing an egg. It can require several days of sitting on the nest, off and on, for an egg to finally appear.
 
One hen, a six-year old Cochin, took a week, recently, to produce her first egg of the season. I needed to put her in a crate on a heating pad for three days running, for an hour or so, and that finally got the egg going. She recently laid her second egg of the season, but it took two days of trying. Granted, she's old, but she's had this problem for years.
 
The other one is an EE and the same age. She's been laying, but sometimes she will sit for hours on the nest without producing an egg. The other day, I was checking on her and saw she was in the process of laying the egg. She grunted and grunted, grunted and grunted. If a hen could get blue in the face from straining, she would have been midnight blue.
 
I was about to whip her off the nest and stick her in a warm tub of water when she finally got the egg out. I took a look at her vent, fearing I'd see a prolapsed vent, but she was okay.
 
If your girl continues this behavior, you can try warm water soaks or place her on a warm heating pad under a towel for an hour. It can often relax them to the point they can then pass the egg, even if it's 24 hours later.