Hello Dennis and All,
If small hive beetle was not your problem then I suspect your problem comes
from a high moisture content, high yeast honey starting to ferment from the
high heat we are seeing.
As I recall Dennis you said earlier this spring you were using honey in
frames from those hives you bought which had been unattended for years. Is
the honey fermented some of those frames? Although bees typically do not
seal honey till the moisture is right sealed honey can pick up moisture in
wet weather (like we had earlier this spring before the drought conditions
we are seeing now) in a weak hive and does many times. Yeasts are  in all
raw honey. Add the high temperatures we are seeing (97 F. today with heat
index of 107) and many beekeepers with high moisture  raw honey  in five
gallon pails in their garage will see fermentation.  Although rather rare in
strong hives I have heard of cases such as you describe in weak hives (nucs)
without the bees to open cells and stop the fermentation and reseal.
Sincerely,
Bob Harrison