testicles changing color while locked up

I’ve been in chastity for a week now, easing into it and taking things slow to get used to the setup. One thing I’ve spotted is that my testicles turn a darker shade of red while locked up. The base ring fits snugly—I can fit two fingers down to the first knuckle between the ring and my balls—so I don’t think it’s too tight. However, I’m slightly worried something might be off? I recently switched to a smaller locking pin, which has made things much more comfortable and secure; with the next size up, there was a risk of slipping out. Does anyone have any advice? Thanks in advance!

MrsL and I are new to this, and I just wrapped up a two-week lock. I noticed some redness too but didn't have any pain... heading back under the key today.

You don't say when this redness happens... is it constant? When Hubby gets an attempted erection, he sometimes turns deep red or even purpleish, but only briefly while his cage pulls on his nuts and squeezes them tightly.:) If you aren't noticing any temperature drops or pain, and your "index finger to the first knuckle test" isn't forcing a fit by shoving your finger into your sack, then there shouldn't be an issue. Another question: are you positioned high and tight in the sack?