Wrestling at the front entrance is a pretty firm sign. Lots of hovering especially in places other than the front entrance is another.
Yes, this is what is happening! I can notice that some of the bees visiting
the entrance are different in color pattern. Also that some bees try to gain
access through the vent holes in the feeder box.
You may just be seeing a traffic jam from such a small entrance. If the hive is strong, I'd give them more of an entrance and see what happens.
I do not see constant traffic jams at the entrance, I just don't think the
population is that high yet. Take a look at the number of bees covering
the centermost frames of the brood camber (link to picture is in previous post)
and tell me if you think that shows a good number of bees hanging
on a brood frame?