Lazy Hen?

Hi

I have a Welsummer hen that I raised from a chick last year. My hens live in a stable, the highest roost bar being about 3 feet off the ground and the lowest about 1 1/2 foot off the ground. Their nestboxes are converted overturned large plant pots.
Lately when I go to let them out in the morning about 7.50am she has laid her egg from the roost bar and it is lying broken underneath her    The hens are usually all still roosting at this time.
She uses the nestboxes fine during the day so why is she not leaving the roost bar to lay her early morning egg?
We have recently acquired a young rooster who is paying her a little bit of attention, could this be the reason?
Any ideas folks? I'm at a lost as to what to do 

Good idea ANHBUC if we can catch him 

I'm not convinced it is the rooster thats the problem tho  as before he came I have occassionally found her eggs laying randomly around the stable. I thought it was because the other hens were in the nestboxes and she couldn't get in so would drop an egg where she was even tho there would be empty nestboxes  we all know what they are like all wanting to lay in the one nestbox