Dozy hen-should i be worried?

So my girls have now been with me for nearly a week and I love each and everyone of them 
However Penny seems rather dozy, she's eating well, laying and generally appears in good health yet she appears to have a nap at the oddest moments! For example whilst eating or when she's foraging for bugs etc she just stops what she is doing closes her eyes and has a little rest for a few minutes, Then she wakes up and carries on with her task.

Should I be worried or is this perfectly natural?

She is 21 weeks, and seems perfectly happy in herself, just a little worried that she shouldn't be napping like this

Make a cup of tea, sit back and watch her for half an hour. Does she move about like the others, sit with ruffled feathers, less interactive, less active......if so be worried, if not enjoy the cuppa.