I was curious also. I asked specifically if there was anything under the flooring like discolored glue or something bleeding up from below.Did they say what caused it?
Nope, they didn't see a thing. They had no clue what caused it, and I didn't push the issue.
Interestingly, the dealer (who is pretty much a one man operation) said I may have to pay the difference between the grades of flooring since my teak was no longer available. But when I picked it up, no charge.