Rune Bug (Rime?)

So this may have been addressed already by someone, but I wasn't able to find a specific post about it.

Since speccing into rime yesterday as opposed to endless winter / pillar of frost I've noticed that sometimes when both frost runes are down one of them will stay fully blacked out and wait for the other to come off CD before even starting to refresh. This means that if you used them at or about the same time that it takes 18.5 seconds before they are both refreshed on there own.

After spending a little more time with the spec it seems to be caused by rime. It grants you a howling blast for "Free" but the next time both your frost runes are on CD if they arent on CD already they will only refresh one at a time.

It's a huge DPS/utility loss and I was wondering if anyone else was experiencing this bug?

I thought this was rime but it's not. since speccing out of it its just happening on everything (Ob / BS). sigh
This isnt a bug and has nothing to do with Rime or any other spec. The Rune mechanics were changed in 4.0 and all only refresh one at at time now. Deplete both runes of one kind together and the second wont start filling until the first is filled, but using rune strike or frost strike will completly charge an unfilled rune sometimes.
ermk. Thanks for the reply.
yeah the fact that runes refresh one at a time for each type and runic empowerment randomly refreshing a down rune to make your strikes hit harder totally screwed us over. thats why you dont see death knights at the top of any dps charts... oh wait..