slight rattle on cold start for 2002 Ford Explorer

Ford Explorer 2002 XLT, 95k km on it.

After a cold start, when accelerating between 20-50km/hr I get an
intermittent rattle coming from underneath the front of the truck...its
fairly quiet but noticeable if you don't have the radio on. After
driving for about 10-15 minutes the rattle goes away, and when driving
faster than 50km/hr there is no rattle at all. There is no engine
strain or noticeable impact to the driving experience when the rattle
is present. Although I can consistently recreate the rattle, it is not
constant...it stops and starts depending upon if I'm coasting,
accelerating, decelerating, etc.

Based on all of this behaviour, I'm guessing its just a loose bracket
or heat shield, however I've only had this truck for a month so I'm
wondering if this is possibly a symptom of anything more serious? I've
got extended warranty on drive train, exhaust, and electrical but not
suspension so I'm inclined to ignore this problem unless people say
otherwise...the dealership is 45 minutes away and its a big impact to
us to lose the vehicle for a few days.

My biggest fear (based on previous experience) is with the dealer
taking everyone apart to isolate the rattle and introducing more
problems.