Only you know your dog so you need to decide whether you think its behavoiral or not. When Sadie was between 5 months to 1 year old she was having problems with peeing in the house. I didn't have her tested because I KNEW without a doubt that it was behavioral.
When she was over a year old she did get a UTI and having delt with her bahavioral problems, I KNEW there was something wrong immediately. She was agitated, had a couple of accidents in the house and was peeing every 20-30 minutes. I wouldn't say that she was having trouble peeing, it was just very often. She also peed quite a bit, considering she was going every 20-30 minutes. We caught it early on so there was no blood.
Some times peeing often is the only symptom of the problem, so if this behavior is completely out of the blue for Ziek then I'd have his urine tested instead of assuming its behavioral (Assuming he's neutered. Un-neutered is another story).