I'm pretty sure he means he felt direct skin contact, not a liquid. As Ark thinks, the sarashi slipped off, and he got direct vag contact on his neck and didn't keep his cool about it.
... I actually thought "Oh, Yamato death-glared Musashi into peeing herself so that she could get a turn" rather than "Musashi's sarashi on her crotch must've slipped off".
Now that you mention it, musashi looks like shes sweating real hard... Which does mean Yamato-death glare...?
The dialogue implies she started sweating because she felt the sarashi slip.
It's fine, no problem.Admiral... are you okay with that?Previously, I have given Yamato and Musashi shoulder rides as part of work, you know?However, there have been things that aren't okay.The sarashi slipped off, didn't it...Yamato would be rocking some attack underwear for that...But until Musashi slipped into her Kai-2, she was in a sarashi, right!?Those two!?...she suddenly tagged out for Yamato right after that. We'll leave the cause down as unknown.Oh?Why a sudden sweat...?No, about that...Hang on, there's a strange warmth around my neck...Good boy,
good boy!