disco 2 td5 heater probs

hi it is nearly a year ago that my td5 blew its head gasket had it repaired by the local specalist in my area now done about 10k been all over europe in very hot conditions with no probs so was shocked to find heater not working on my way to work on arrival i checked header tank it was showing a low level of coolant i squeezed the top hose and got no change in coolant level so i waited for it to cool raised the header tank and all the coolant disapeared topped it up opened the bleed screw on the top hose until coolant came out reinstalled everything started car and hey presto we have heat again. i will get to the point as i only have 2 weeks warranty left on head gasket is it advisable to get them to check it or get another garage to ?
thanks for looking

if you havent checked coolant in a year ,it could just be natural loss ,most seem to leak a little from somewhere but not harmfully if you check coolant with bleed screw removed often

Check the heater hoses and the hose that goes round the back of the head.
Could have rubbed through

thanks guys will check tomorrow