My 90 Accord LX auto- if I remember correctly - turns about 3000rpms at 70mph. So it does sound like yours is running a little high. Does it feel like the torque converter is "locked" at those speeds, or is there a little "slip" if you tap the accelerator at those speeds? I've noticed that the lock-up function is worth about 400-500rpms. Perhaps your torque converter is not locking up.