Snuggly Chickens

Well - I came home from work a bit later this evening.

The chickens seem to be retiring to the coop of their own accord now any time from 1800 - 1830 ( dusk basically ) which I'm pleased about.

I've noticed though today that they've all decided to try and squeeze into one nest box instead of on their perches!

One of them seems to prefer to be on the perch though which is good but there's one chicken who seems to be 'squished' either in the nest box or when they all huddle together in the coop at night. I've tried popping them back onto the perches but they just keep huddling up. It's not especially cold so I'm not sure why they are doing this.

Any ideas? Cause to be concerned? I'm of the mind that they're doing this because they're comfortable but any advice welcome.