No offense to your girlfriend's dad, but take it to the dealer for a couple reasons.
1.) He could be wrong, no matter how much of an expert someone is on something, it could always be overlooked. Going to the dealer means that if they miss it, they pay for it.
2.) Get it in writing FROM THE DEALER that they could find nothing wrong with the truck. That way, if it does break, guess who's getting a new Dodge Ram (09 anyone??)
3.) If there is something wrong with it, the dealer will be able to give the best diagnosis (plus you get a sweet loaner that you can rag the piss outta
) Once you have the diagnosis, then we can give a solution on how to fix it.