Yes, it might be. Try not to pin this smell to that one you're having before AF. 2ww is always overstressing. Mine somewhat changed in colour. Urine got darker surely. Then in 2 days I began having pinkish spotting turning to brownish after a couple of hours. I called my nurse at the clinic and she told me there was nothing urgent. Moreover she said tose were more likely good signs for me. I got bfp then. Currently prego with baby#1.
Do drop us a line, please. Fingers crossed!!