I understand your concern. Unusual noises while idling can be caused by a number of things. It could be as simple as an exhaust leak or loose parts, but it could also indicate more serious issues like problems with the transmission or engine components.
Regular maintenance is crucial, but some issues might not be apparent during routine checks.
My advice would be to take your truck to a trusted mechanic who can perform a thorough inspection and diagnose the problem.
It’s always better to address these issues early on to prevent potential damage.