Wet dream?

So my husband and I haven’t had sex since Friday, today as I was cleaning up our bathroom I found 2 pairs of boxers with milky white stains about the size of a quarter in the crotch area. To me they look like pre-cum. Is it possible that when he gets hard in his sleep and then flaccid again that some leaks out? Or should I suspect something else? I’m trying not to get worked up but we’ve had issues before. I don’t plan on bringing it up to him but want to know if I should be on the look out for more suspicious activity.