Coal seam fires aren't particularly rare, and while they can occur "naturally", almost all of the thousand or so burning around the world at any given time (some for months, some for centuries) are explicitly linked to mining.
Sure, all the ones we know about today. It's a bit of an anthropic argument, though. We only know about the coal seams that have survived long enough for us to find them; and, almost universally, we've chosen to exploit the seams we've found. That leaves two questions unanswered:
• What would the statistical yearly probability of a coal-seam fire be for seams we find, check up on, but never mine? (We know of a few seams in protected areas, but I don't think we know of enough to have any statistical power. Also, the natural catching-fire rate might be, say, one per thousand years, which would be a bit like the pitch-drop experiment in its requirements, yet would still mean that coal seams catch fire pretty much "as soon as" they reach the surface, in geological time.)
• More interestingly: how many coal-seam fires have happened historically in the Earth's 4.2 billion years being around, that finished and burned out all the coal, and now there's just a cave there? Or ex-cave sedimentary layer, given that these caves tend to collapse? Can we tell when such a cave/layer was previously a coal seam? (I assume so, because soot, but can pressure-treated soot be differentiated from other kinds of naturally-occurring mineral striae?)
https://en.m.wikipedia.org/wiki/Coal-seam_fire