Generally, permits are not required for panning, it is looked at as "casual use". To be safe, make a call to the National Forest office in the area you are going to be in, and the BLM state office if going to be on BLM ground.
If hitting the GPAA claims, take your guide and member card. Be sure to do your homework on claims that are active if not going to GPAA claims. That info can be had from the state BLM office, just look up on LR200 by Township, range, section. LR will break it down to a 1/4 section, anything further can be had through the state office.