People already addressed the sperm plugs. I'm wondering: Is he hungry? My males eat and eat and EAT AND EAT... and then they suddenly stop.
If he's still hungry, I'd feed him up nice and fat for a month. If he's not showing interest now, I'm guessing he'll show it in another 100 or 200 grams?
(of course, my 1200 gram 2008 boy just decided to spend two weeks cuddling with his girl before getting down to business. GAH.)