I just built a newly constructed home. Contractor installed White oak hardwood was installed with Old masters stain this past November. Moved in in December, started noticing these marks popping up all over kitchen (probably like 20 marks in kitchen) and dining area (10 in dining). They don't photograph well and are easy to miss in the daylight but are really noticeable when you know what you're looking for. They look like discolored marks like if there was a burn on a table. Contractor and hardwood sub contractor have come out and neither have seen this occur before. Their solution is to sand off(might not be the correct term) the poly leave the stain and reapply poly. But can't guarantee this will work as they haven't seen it before. Does anyone know what this is or what caused it? It's definitely under the poly or stain not on the surface.

Looks like sweat drops.