That said, a few hours mowing, no matter how harsh, shouldn't dull the blades as you suggest. Only if you were "scalping" the lawn to rejuvenate, or cutting in very sandy conditions might this happen, and even then 3 or 4 hours still seems excessive. McLane doesn't have the same quality as Tru-Cut, Trimmer, and Locke in their reel and bedknife steel, but even then this difference is a matter of percentage, not orders of magnitude.

It's possible that the cap screws holding the reel bearings weren't fully tightened, permitting the reel to gradually be out of adjustment. One end of the bearing holder is a pivot, the other end can move along an arc, permitting adjustment closer to for further from the bedknife. Bedknife could also be loose relative to the frame.

If you bought machine new, I'd ask the original seller, or their authorized service to adjust the reel/bedknife under warranty. If you bought used, I'd either have the reel adjusted professionally, or if you are handy, try to do it yourself. The goal is not actual metal-to-metal contact, but rather to be close enough the strips of paper will be cut but scissor action, rather than tearing. If you adjust metal-to-metal, the reel will gall against the bedknife, and then you are looking at a very expensive repair.