Well, I noticed that gap on mine as well. Not sure if it will make a difference or not if it does get sealed. This is my first year using a wood stove and I am pretty sure in a few months when im done for this year, I am going to discover a few things I will want to fix. I am glad you reminded me of that crack. I also think that where my liner goes into the stove could use some sealing. One thing I wonder is if it is ok to seal that gap or will it shift too much as it expanded with heat etc. Another concern of mine since I have never used cement is if it is easy to remove. If I use it to seal the gap with my SS liner and then later get a different stove, can I simply hit it with a hammer or something? Went to Lowes today out of curiosity to see if they had the cement. I know ACE around the corner has stuff for pointing up a fireplace mortar... Same stuff? Good luck with the stove and please let me know how it goes. FYI, buy some longer screws at home depot to attach the blower. I have my blower about 2 inches off the wood stove for better circ. It's a nice 73 degrees in here tonight with 69 upstairs.