They should be fine. Bulbs are much more cold tolerant than you think and it is often the case that the foliage appears rather earlier in the season than expected, depending on weather conditions. It is possible that the exposed foliage could be damaged by some severe cold, but that should not affect the flowering - which will very likely still be at the appropriate time for your area - or the continued viability of the bulb.

If you have any leftover leaves hanging around, they would make a good insulating mulch to prevent any further damage and the bulbs will grow right through it.

Great idea on the leaves. I also have tulip leaves coming up way earlier than usual (and buds on my trumpet daffodils ahead of my minis - strange winter here!). I might use some of my precious shredded leaves on the tulips.