Is my axolotl stressed out?

Hi everyone, new axie owner here

I've had a couple of lucy axolotls for about 3 weeks, they are about 2-3 months old now and everything has been great so far, but these past couple days I've noticed a change in one of my axies. Basically I feed them bloodworms every day once and just let them eat until they lose interest in the food and clean the rest out.

I've noticed that this one axie is usually really jumpy in the mornings before I feed them and tends to swim around the tank a lot and I imagine it's because he's hungry and looking for food. His body is also a distinctly redder/pinker shade in the morning when he gets jumpy while my calmer axie does swim around as well but not nearly as much as this little guy.

Also sometimes once they are done feeding, the jumpy one will have his gills turned forward and this happens a bit throughout the day but his gills don't stay that way the whole day from what I've seen. I've read online that they are stressed if their gills are turned forward but for the life of me I can't understand why he would be stressed.

I have a 20gal tank and two filters, one is a sponge filter and I have a regular HOB filter. I doubt the sponge filter creates a lot of current on the bottom of the tank since the bubbles go straight up to the surface, while I have a plant dispersing the water current coming out from the HOB so they have pretty calm water on the bottom. They have hides as well and one airstone that came with the sponge filter package I got online. Also no substrate yet per recommendation of the breeder.

Water levels are about the same every time I test:
PH: 7.6 - 8.0
Ammonia: 0
Nitrite: 0
Nitrate: fluctuates from 0 - 5.0 (getting additional filter media to help fix this one very soon)

Water temp: always between 64-68 degrees Fahrenheit

Also I do 50% water changes every 2-3 days and clean all the nasty I can find often. I use Prime to detoxify the new water when I do water changes.

So do you guys think this particular axolotl could be stressed out? If so, I wonder why his companion is much calmer pretty much all the time?

My thoughts are that you just have two different personalities.
An active axolotls...especially the light coloured one, will often appear redder than a sedentary one as the blood pumps around more.
Their gills often flop forwards...especially if they have heavy filaments.
Can you post pics if still worried...but sounds fine to me!

This is how I found them tonight after coming home from work, they both had their gills slightly pointed forward... could it be that this is just how they sleep? Since it happens more often at night?

No idea why the pics are sideways sorry lol