Cardboard Like Flavor in an Ordinary Bitter?

Brewed an ordinary Bitter last weekend. Just took my first Hydromter reading, and I went from 1.043 down to 1.013 in that week. Started fermentation at 64 degrees, then last weds. I brought the Carboys upstairs to the main living area to bring the temps up to around 68 degrees (I really want these beers ready for this weekend for a Party). I used White Labs WLP013, London Dry Ale Yeast for my Yeast. I just tasted the Hydromter samples, and I am getting a stale, Card Board like flavor to both of the carboys. I made sure not to smoke a cigarette this evening to have a clean palate ( I find that if I don't smoke for about 4 hours, my palate is that much more in tuned to fine flavors). Just took another sip, and yeah, tastes Stile. Maybe I am just over worried about this beer being ready for this weekend? Keeping in mind that it's at 69 degrees and not carbonated, maybe it's just me. I have brewed this batch once before with great results. Anywho, what could contribute to a card board/stale flavor to a beer from the primary?

Hmm. That's a common off-flavor - sounds like oxidation to me . Check out the following links, which are pretty helpful in troubleshooting beer:

How to Brew - By John Palmer - Common Off-Flavors

Troubleshooting – Off Flavors in Beer

I'm not really sure what you can do about it. I fear there may be nothing to be done, though there are many more experienced brewers on here, so you may get more constructive advice from them.

I would think oxidation also, but I doubt you got that already. I think maybe you should just wait and see. The fermentation looks good. Did you move the carboy before or splash it around at all?