Thats so sweet of him!! ..if the dynamic is good, I wouldn't ask! lol When you have a lot of conversation time its probably easy to make those things come out.
I usually use very vague terminology when I try to start and explicitly imply that any amount of wetness is good.
I'm really into it, I dunno, I'm not very social so women come along only every so often who show an interest, it is a big gamble to put something so rare on the line for a fetish. But sometimes, I just want to be like "I'm going to spank you until you wet your panties and your going to like it" but I can't say it and so I just feel constrained.