Vets or vet techs, UTI or just too much water?

I have a 6 mo old beagle terrier mix going on about 8 lbs. He's been house trained really well for about 2 months. Tonite we took our usual walk and he peed twice between 8:30 and 9:00 and then about 9:15 he peed in the house no warning. Took him out and he peed again about 9:30. Then we were sitting here on the chair and he was sleeping and woke up and started licking his and he had peed I guess in his sleep about 10:15. Took him out again immediately and he peed again outside. He had about 3 to 4 oz. of water when we came in from the walk at 9:00. When he went on the chair I noticed there's no blood and seems clear, no puss or gunk. Now he's sleeping again. Seems to not be in any pain. What do you think?