bees clustering at entrance in morning ?

[Dr. B in Wisconsin]

Hello
I have 2 bottoms,    queen excluder,     shallow honey super,    inner cover " box with top entrance" ,    empty box with sugar water jar and then the top cover.

Bottom 2 have lots of brood and things look fine.

What I have noticed this morning, the temp is 60, is that the bees are in a clump outside the top entrance " by honey super "and I drilled a vent hole in the honey super a long time ago and they are clumped there also. The clumps of bees are only outside the honey super only, I opened up the top of the honey super and they are starting to draw out the comb some, maybe 2 frames less than 50 % ,  other empty frames have some bees on but there is room on the outside frames for them to go if they wish. Is this normal ??? The clumps are not that big, maybe the size of a cell phone.  I thought that all the bees would go inside on a cool night ??

I drilled 3/4 holes in the bottom 2 boxes for air vents a long time ago, and also have a bottom entrance, they like to come and go through the holes and hardly ever use the bottom entrance. This is my first time at this. I hope this give a clear view of what the hive looks like.

[Paynesgrey]

I'm new too, but think that they are probably guarding the hole against wax moths, SHB, and anything else that may want to sneak in at night. If I take a flashlight out to our hives at night, (like to bring in the cold smokers :) ) I see the same thing, there is a cluster at the entrance.