If it is your honey, then you know what is in it. No worries there with foulbrood or chems. If the uncapped honey had too much moisture and sat around for awhile, then it could start to ferment. Not good. There would be your problem. If it was stored in a freezer, then no problem. I feed back uncapped honey. I pulled 4 or 5 supers out of the freezer this spring for open feeding.