Quick question on supply shaded hexes

[iberian]

I have a quick question on the supply model. If you switch on the supply area, you are able to see which hexes are on supply, and which will be able to receive replacements. There are also small truck icons to show which hexes are being supplied by a truck unit.

As you see in the enclosed picture, I don't yet have a truck supply unit (they will evolve later), and still I have truck shaded hexes (as shown by the red arrows). I only have "leg" supply units, so... what's going on here? Are the small trucks also valid for leg supply?

[JSS]

The truck icon you see on the yellow supply hexes is telling you the supply came from a supply unit (vice a supply source or strongpoint).   Burst of supply mode is not indicated.