The logic here reduces the minZoom set by leaflet

[ChengXueqing]

mapbox-gl-leaflet/leaflet-mapbox-gl.js

Line 117 in b3affa6

zoom: this._map.getZoom() - 1,

When there is a layer / marker on the map, this setting will cause the overlay to shift when the zoom is equal to 1 or 0.

[jgravois]

pretty sure #130 resolved this.