Twice, I had overweight charges processed against me for very minor weights (~2-3 lbs) at SJO. That was pre- new EP 3x32 kg / 70 lbs allowance.

A little off topic, at some Caribbean stations with turboprops or regional jets, regardless of overweight, bags can be left behind if density altitude vs. gross weight issues become problematic - worse, IMO, than paying for some overweight or scrambling to repack at the counter.