Is Messick Farm Equipment the dealer you're talking to? /forums/images/graemlins/grin.gif
Here's some text from the Kubota Warranty:
<font color="blue"> The length of the warranty is not the same for all models. Some models have a specified time period only (6 months, one year, etc.) while others have both a specified time as well as an hour meter limitation. In the latter case, the limitation first occurring (date or hours) determines whether or not a product is within the warranty period
BX, B, & L Series tractors - 24 MONTHS or 1500 HOURS (whichever occurs first) (Powertrain – 36 months or 2000 hours, whichever occurs first) </font>
I would make sure that the 70 hour discrepancy was noted in the purchase and warranty documents, if you pursue this.