clear discharge

I've had my cat for about a month and when I got him from the shelter he had been neutered only a couple of days prior to the adoption. They estimated Seamus to be 1 to 2 years old. Anyway, when I first brought him home I noticed that he seemed to be "leaking" a clear odorless discharge from his hindquarters. When I brought him to the vet I mentioned it and she checked him over but didn't find any problems. After that it seemed to stop, but I started noticing it again the other day. It isn't constant, just every once in a while. I've noticed in particular that it happens when he is laying down, very content. He likes to knead with his paws and i've noticed this behavior when the clear liquid secretion occurs. I'm wondering if he's trying to leave his scent? I know that male cats do this and he was only neutered very recently. I just thought it odd that the secretion doesn't have an odor. He seems otherwise healthy and happy. Should I be concerned? Has anyone else ever experienced this?

If it's been a month I would give the vet a call & ask. A lot of people think you have to take the vet in, but I call my vet all the time when I'm concerned & she lets me know if they need to come in or not.