Normally the builders standard warranty is 6 months for minor defects & 18 months for major defects, so legally their warranty has expired. I would however, write to the builder & ask them to inspect the problem. Normally window manufacturers give a 10 year warranty on their products, so the builder would give them a call & ask them to attend to the problem. If it's not a structual issue (windows generally don't count), then Homebond is of no use to you my dear.