We have just had hardwood floors installed in our new house. Vinel was put down as a moisture barrier and then the oak strips were glued to the vinel. We now find we have hollow sounding spots on our floor. The floor "pops" in a few places. Does this mean that the floor has not been glued down properly? If not, what is the remedy? If we leave it like it is will we have trouble in a few years? Thank you for your help.