I just returned from walking with my dogs (on leash). I've seen this happen before and find it interesting..
So, we're tooling down the road (very rural here...all dead end dirt roads), dogs stop to sniff here and there...Then, it's time to turn back and something we literally passed less than 10 seconds earlier (and was NO big deal) has suddenly turned into a HUGE SMELL DEAL....I mean, they went berserk! I almost got pulled over and dragged, it was THAT good!
It's fascinating and all I can think of is something changed weather-wise, and smells are rising differently? I bet One Best could explain it.