That's how it usually works with Li-Ions and other battery types that use plates. Lower capacity for a given volume results in lower internal resistance and a higher C rating. Higher capacity for a given volume comes at the cost of a lower C rating. The reason is that the plates are thinner to fit more in there for a higher capacity. Thinner plates have more resistance which increases heating and lowers the drain limit.
I good rule of thumb is to use double the drain limit for your worst case load. So, if you're using a 1 Ohm atomizer, highest drain would be about 4 Amps so you'd want a cell with at least an 8 Amp drain limit. You could use a cell with a 4 Amp drain limit for a 4 Amp load, but you get big losses and heavy wear when you run a cell at its limit.