Why do my ferrets glow?

I'm using the ferret rune for companion. Now I have 2 ferrets running around collecting gold and adding paltry DPS to my arsenal, which is awesome.

What I don't understand, however, is why they keep glowing when they pick up gold. It doesn't happen every time, but it only happens when they collect gold piles. They will get a giant blue glowy shield (far, far larger than the size of the ferret) for a few frames, then it will go away. It comes with a sound effect and everything.

What is going on? Do these ferrets have some kind of extra ability on top of the stated tooltip?

I noticed today that when they could not reach a pile of gold, the blue bubble kept flashing over and over.... until my game locked up(it flashed approx 30 times). But so far have not noticed it's frequency related to size of the pile of gold. It has flashed on a 5 gold stack and a 245 gold stack. From my testing I would say it has to be something related to them being unable to reach a pile or becoming stuck.

EDIT

More testing done and I'm confident in my answer. When they are unable to reach a pile of gold that is when this blue bubble and noise happens. I have been able to make it occur over and over (in fact everytime I open the chest while trying to get the mysterious cave to spawn) in the Dahlgur Oasis area. Where the alchemy npc spawns, there also spawns a chest by a set of small steps and a wooden platform. The chest is directly across from where the mysterious cave entrance spawns when it does (sometimes it is a bone pile also). When you open the chest the gold either drops under my character or on the platform. The blue bubble will keep flashing over and over and the ferrets never pick the gold up. As soon as I move my character the gold picks up and the bubbles stop. The blue bubble is just a way the developers put in the game to let the player know the ferrets are trying to reach a pile of gold and cannot.

Hopefully someone can try with their ferrets and mimic the same results. Oh and I am using the Templar as a companion

I see the same behavior and haven't found a good reason for it so far. Some personal theories that didn't work out:

• Indicates when the ferrets pick up a large pile: No, they can glow for small change and then silently pick up a large pile.
• Every X amount of gold picked up: I kept a close watch on my gold at hand and the ferrets' glow but this also shows no correlation
• Some kind of interaction bug with Enchantress' Powered Armor skill: Had this conjecture since I first realized it while with Eirena, but have also seen it happen in multiplayer

One conjecture I have (that is untestable) is that it is simply a means to occasionally identify your ferrets, which makes sense in a team game with multiple DH/ferret - however, DH pets are non-targetable and pretty much fire & forget, so that doesn't make sense either.

Things I need to try:

• Checking if it boosts GF as @Xenogard posted - doubtful of this; but it may just be a periodically refreshing 10% buff? (afaik ferrets add 10% GF)

I did manage to replicate what @DedBob posted, that ferrets glow repeatedly when they can't get to a pile of gold nearby. Not sure if that is the only reason as they also glow when picking up piles of gold right in the middle of the floor - this could just be a pathing hiccup, but may indicate other reasons to glow as well.

An observation from the inaccessibility of piles is that ferrets may not benefit from +gold radius items on the player, and have 0 radius always.