Paid a flooring contractor almost $10,000 to install new hardwood flooring next to our current hardwood flooring. The new hardwood flooring is interlaced into our old hardwood.

Attempt #1 - They laid the new flooring. Sanded both new and old. Applied a stain, sealer and poly. We were excited, to get back moved into our house.

Problem #1 - As soon as we walked in, we noticed little bubbles on some boards. Ugh. They came and spot fixed those areas of bubbling.

Problem #2 - A few days later, more bubbling started happening. They had to come again and fix the bubble spots.

Problem #3 - About a week later, we started seeing white lines popping up everywhere on the NEW section floor, but not where the old hardwood flooring was.

Attempt #2 - They came back, sanded everything back down, re-stained, re-sealed, and re-polyed.

The contractor said that they are giving the stain extra time to dry this time around (3 days instead of 1).

But now i'm worried.

Is the contractor's fault? Are all these issues just a freak coincidence? Why did the bubbles happen? Why did the white lines only happen on the new flooring and not the old flooring?