My 7 month old Chi mix has recently started peeing much less than usual. For example, she went out at 5:40am and peed, and I took her out again before work, but nothing. Then I took her out at lunch and she peed. My husband took her out at 3:30pm and she didn't go. She went at 8pm and I took her out several times between then and 11pm and she still didn't go. She just sniffs around and sits down. She's acting totally normal, eating and drinking normal. She doesn't have any symptoms of a UTI or bladder infection. Is she just able to control her bladder better because she's getting older or should I be worried?