HRX217HYA. Not cutting level.

So I bought this mower 2 years ago. A couple month ago, a neighbor was over as I finished mowing and commented that i must have a bent blade, it was mowing crooked.
As I looked at the fresh-mowed lawn, I could see that the grass on one side was ever so slightly shorter on the left side of the cut. In retrospect, I had noticed this before and hadn't thought much of it. It grows up in a few days and is not noticeable.
Now I'm pretty handy so I KNEW it wouldn't be a bent blade or crankshaft. Checked the wheels. OK. Looked in the manual. Nothing of note.
Search the internet. Find a few references but nothing definitive. Other than it should be a warranty issue. Well heck, it's got a 5-year warranty so I take it to the Home Depot I purchased it from and had it sent for warranty service. Specifically, I had the associate state exactly how it was cutting and that it seemed to be an issue of the blade in relation to the deck. (Oh, yeah. I did check that. It was off.)
Warranty center solution: Can't find anything wrong. Changed the blades, non-warranty, $70. I have not got the machine back yet but I KNOW it is not fixed and is going to mow the same.
Has anyone had an issue such as this and what was the solution?

Thanks so much.