Watch them. I sometimes get inflamed cycts--few since LC, actually--they may resolve, they may drain (yuck!), they may stay around. They could be cancerous, but my doctor's rule of thumb for cancers is that they are very hard, and if yours are squishy, you might be OK.

suspect it's not directly related to exercise, although it could maybe be too much lactic acid building up or something similar.

Observe, and make sure you've noted when they appeared on a calendar so you can give a decent history if you decide to see a doctor. If they increase much in size (I've had them go to almond and then go away on their own) or turn purple or more appear, you probably want to get help.