Why does parasitic capacitance seem to increase with winding pitch in this air coil calculator?

Title - I am experimenting with this Air Coil calculator:

https://k7mem.com/Ind_Coil_Ind_Calc.html

One thing that baffles me is that "Parallel stray capacitance" seems to increase as the distance between windings, ie. winding pitch, gets larger. For example here are some parameters of a coil I've been winding around a plastic jar:

- Mean Diameter 90mm
- 40 Turns
- Coil Length 90mm
- 28 AWG
- Design Freq 1MHz

This produces a winding pitch of 4.5mm, and calculates a stray capacitance of 2.09pF.

But if I shrink the length of the coil to 60mm, which decreases the pitch to 3mm, with all other things being equal - that calculates a stray capacitance of 0.03pF.

What am I missing here? I would have thought more separation between windings would reduce capacitance.