In my opinion you can spend all day looking over a new unit and still miss some things. Take it out and use it, start making a list of repairs and adjustments and don't get all bent over a one hour PDI. Heartland is a great company to deal with but I'd be willing to bet they could care less how long your PDI is..B.O.
Things can be missed on a PDI and things can break and need warranty repair but I think The OP's issues are quite common with dealers. From the experience I and a number of other posters have with Dixie it would be the wise person who would not sign any papers or drive out of Dixie's parking lot until that rig has been gone over several times and every thing is working. Why would anyone want to take a rig out prior to a thorough inspection and repairs made? We too often hear about things the new buyer missed or the dealer blew off and then the buyer has to repeatedly return the rig for repairs and then wait months to get it back. Remember, once you drive off you are then on the dreaded "wait" list for repairs because the dealer is "busy".