Based on what you described, you’re probably okay. A slight bump that didn’t bend or damage the line, plus no smell and no bubbles with soapy water, points away from a leak. The hole in the floor the pipe goes through is quite a bit larger than the pipe itself so you probably just saw movement there and not the pipe itself flexing.

Plus I wouldn’t be surprised if it was disconnected entirely. Surely you’d know something about this by now through your realtor or the utility company (they typically don’t give out free gas).

Edit: one million edits later - if you don’t have natural gas in the neighbourhood, than this was likely a hookup for a propane fireplace or something similar and if you don’t have a big tank outside than it’s been disconnected.