Clicking on my mirage drive?

Every once in a while, not all the time. I will get a click at the end of my stroke on the left side, just about 1/2 inch until my flipper would hit the hull. It will happen no matter how hard/slow/fast/gentle I'm peddling
(Opening paragraph to a sex novel?)

I pulled it out, and have tried to repeat the noise while out of the water, and the closest I got was maybe noticing one of the teeth making contact ever so slightly with the chain. It's hard to explain, but it seems like for that one part of the stroke, the sprocket and chain are not lined up entirely. It will happen for a little while, then stop.

Something I should bring in for service, or is it a simple fix with minor adjustments?