I had the same problem with the Giants/Eagles game. Exactly 3:10 recorded even with a 30 min pad.
The day before, however, I had 30 minute pads for both playoff games (one game on each of my hr20s) and the pads on both games/machines worked fine.
Another observation: during the Giants/Eagles, trick play was EXTREMELY choppy. FF and rewind would take one or two seconds to even begin, and then FF would stutter, stop, stutter.
The Jets/Patriots game was just fine. It was recorded on my other HR20 so I don't know if it was a hardware or software problem.
On the same machine I had the stutter problem, I also had a BSD on a Saturday recording of a program on Speed Channel.
Next week, I will record the playoff games on both machines and see if (both/neither/only one) have any problems. If this week's problem hr20 is the only one with problems, it may be time to consider that it may be in the hardware.