Just out of curiosity, was last year your first or second year growing them? The reason I ask is that there's a big difference from 'starts' to a plant that's got a year's growth under it's belt. Sometimes it takes two years for them to really get established.
If they've been in the ground for a couple years, then yeah, it's most likely the mild weather. Mine are pushing, but nothing's really broken ground yet. The rhizomes I'm digging are to the point where they should be in mid April. Soil temps have everything to do with it. Hopefully Ma Nature doesn't do a 360 on us or all the excitement will be all-for naught. What ever she decides, you just gotta roll with it!