They're cold, they will make a bit more noise in the winter, especially the 2nd and 3rd winters. Just depends on how much salt and snow they see. If you like, just replace them, or live with it.
I took mine to my dealer (modesto Mazda, CA) and they put new front bushings on fixed the problem right up!!!! for free mind you.... If that helps yah.
I got my front and rear bushing replaced for free at the dealer and the sound went away. Just make sure they order the right parts. 156E bushing for the rear and 156A bushing for the front.