I normally use super glue for gluing in hook hangers, line ties, ballast, etc. I ran out of super glue the other day and have been using 30 minute epoxy for this until the next order of super glue arrives. I use a syringe with a large bore needle to shoot the epoxy in the drilled holes. The needle isn't usually long enough to reach the bottom of the hole so I try to poke it down to the bottom of the hole with a piece of wire. This, to say the least, is a hit and miss deal.
The temps have been a little on the cool side so after gluing in one of the hook hangers I placed it close to a ceramic heater. Not directly in front, but a little off to the side. Apparently their was an air pocket at the bottom of this particular hole and it expanded from the heat. When I went back to check on it an hour or so later I noticed the hook hanger had been partially pushed out of the hole.
Just wanted to pass this on so hopefully it will save someone else from this headache.