We replaced the wood burning fireplace with a gas one. The company that did the install did a lot of air-sealing behind the fireplace and in the chase cavity. When they installed the fireplace (not an insert - they ripped out the old one and were able to install a new one from the outside-in), they were able to get it flush on one side of the hearth-opening but there was a smidge of a gap on the other side (see picture). They caulked behind the fireplace and now that we've used it for a full winter, we are feeling a draft on the side that has the gap (where my finger is). Do you think I can shoot a bead of fire-grade/high-temp caulk into that gap on the house-side of the fireplace or would there be issues in doing that?