“Rumble” in groin when pumping?

[Jack1104]

Lately I noticed when I’m pumping when I get towards increased resistance, I’m feeling a “rumble” in my groin where I believe the tubing goes up to the reservoir. It happens when there is increased resistance, like if I pump when things are “cold” or when I’m trying to two-hand get those last squeezes in. Sometimes also when I deflate. Titan original. Anyone ever experienced this before? Any ideas?

Thanks!