Received some SED -C- tubes and have a few questions. I don't have much experience with tubes overall and none with SED's. Two appear to have a hairline crack that runs vertically up the side of the tube. They just enter the curved portion, top and bottom. The tubes have not frosted at all. I have not installed them. Is this reason for concern? Some have small bubbles in the glass at the base. Less concerned about it, but wondered if it's common. Thanks!