Probably muscari - one of the drawbacks of the grape hyacinths is that they throw up foliage in fall and then stay green all winter and bloom in spring - or maybe it's an advantage. But it can be a nuisance if you want to make a clean sweep of the area they're in. Don't worry - the usual thing with them.

That's good news, that this is usual behavior. I do recall, now, that not long after planting the bulbs last year, we had a period of very warm, spring like weather, and that the bulbs sprouted a little. I thought it was because of the weather. The leaves got nibbled by something - deer, woodchuck, I'm not sure, but recovered fine. Looks like they are naturalizing nicely - the clumps are much larger this year.

Thanks for the info :-)

I have hyacinth and lily bulbs trying to break ground, so I just covered them with more soil - they will have to wait until spring in my garden.

My bulbs do this every year, even throughout the winter after warm days. As long as the flower buds are safely underground, they'll be fine.