I have a Guinea pig who spends a lot of time with us. We’ve had him for a few years. I notice when I hold him for a long time he will start to heat up his body temperature will suddenly get super super hot and he will give off this sort of warmth from his entire body. During this his ears turn red. He does this when he is visibly relaxed as well. I noticed he also does this on my moms lap when she holds him every time. Any idea why this happens? His ears stay red along time after putting him back in his cage