Rebuild parts are only $200-$300, finding the problem before internal hard parts damage is a wise idea. Don't drive it if it shows major symptoms. Burned up transmissions often fail multiple times.
That being said, check the fluid carefully, keep an eye on the fluid level. Do you have a trans cooler, has the truck been used to tow with?
Chris, am I correct in assuming that the trans is an A4LD or 4R55E, both suspect transmissions?
If the overall feel of the transmission is good, when in Drive, try installing a TransGo correction kit. Check here first with searches, for similar symptoms. Find the possible parts that you might need to fix the problem. Buy those parts from a trans parts shop. Find someone who can install those parts, with the TransGo kit.
Spending a couple of hundred dollars for parts that may prolong the transmissions life, is better than waiting for it to fail, and hoping a rebuild will keep it from happening again. Good luck,