Model # is C26-21-1

I had the cover off of the furnace today and thought I caught a whiff of natural gas...not overpowering and only detectable if I stuck my face right up at a certain place in the is not spread to the cellar and doesnt seem to be growing

Take a look at this pic

The smell is coming from the upper right hand corner of the silver box the best I can tell...right to that the right of that top bolt on the very corner(s) of each side of the box next to top bolts there is a small opening into the box...they look like they were built that way

You know maybe it has always been like this and I am just noticing because I have been super wary of smells lately......

Is this something I should be worried about?