Extruder retracts before start of print

Hi All,

My extruder seems to retract about 3-4 mm just before starting to print, this menas that it will only print half of my "purge line"

Could you please tell me what's wrong?

This is my "start" Gcode:

;FLAVOR:Marlin
;TIME:2826
;Filament used: 2.57272m
;Layer height: 0.25
;Generated with Cura_SteamEngine 3.4.1
M190 S60
M104 S210
M109 S210
M82 ;absolute extrusion mode
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 ;move X-Y-Z to min endstops
M420 S1 ;Enable Mesh leveling
G92 E0 ; zero the extruded length
G1 X35Y10Z0.2 F5000 ;move out of print volume
G1 X80 E9 F500.0 ;start purge line
G1 X120 E12.5 F500.0 ;finish purge line
G92 E0 ;zero the extruded length

Thanks :)