Hi Steve,
Not all hives are on the same time line in terms of development. One of mine has not been out for weeks even when all the others were flying. They are a late swarm which is being fed fondant now so less roughage, but I can hear them when I put my ear to the hive. Some of the others collected pollen a couple of weeks ago, but the inclement weather put a stop to that.
It is not necessarily bad to have some spotting on the hives, so you have had some cleansing going on. You have seen the bees on the frames, so that is good. This time of the year you will have the least bees in the hive, as the old bees are dying off and brooding has not started in earnest. Everything is probably ok, but I know one cannot stop worrying about them. If you put them to bed with enough stores, Q+ and treated for varroa then the rest is up to the bees. I can't wait either for a +8C day to see them flying, but at this rate we will have a long wait.
Two beeks thinking alike, can't be bad!