Congratulations! It's a very popular HG model. Sounds like your slide is out of adjustment. If you have a good dealer, they should do it under warranty and in about 30 minutes. You can do it yourself too. The manuals for your through - frame slide are available at
www.lci1.com. Sorry I can't link it directly from my cell.
P.S. - the adjustment you need is the "synchronization" if one side is sealing properly and the other out as you describe.