New 04 F-150 Question

Hey all, I'm a newbie here! I just bought a new 04 F-150. When you start it up all the gage needles bounce for a couple of secs. It just started yesterday after 2 weeks of ownership. Dealer appt. on friday, but I'm just curious if this has happened to anyone else and what it might be and what the problem was. Anyone know? It's an XL W/4.6 Triton. When starting it acts as tho the battery is low but when it catches All the gage needles vribrate a few seconds then smooth out. If I shut it off then restart it every thing is normal. It only happens when it sits for a while. Thanks for any info

Took it to dealer. Found out the battery was bad. Kinda strange for bein only 2 weeks old. They did a load check to make sure nothing was pulling juice, gave her a thumbs up :bigthumb: and sent on me on my way