You are probably just fine. The plants that survive the winter (and the mulch will help them survive it) will push up right through the mulch. Mulch doesn't really stop plants from growing, it just helps keep down weed seed germination from lack of light.

There may be some wimpy plants that can't push through 3" of mulch, but most can.

Your hostas I know for a fact won't have any issues at all as the mulch invariably 'moves' over the spot the plant was in my garden with the repeated snow/melt/snow cycle we get here. In the spring I think 'where are my hostas?'. Hostas are fairly late to sprout in the spring so it is easy to fret at their absence when other things are up, but they invariably push up through the mulch in their own time.

In other words, don't worry about it and if you can't help worrying then just go out in early spring and rake away the mulch until the plants come up. The mulch during the winter is a definite plus for overwintering those plants marginally hardy in your zone so you have done a good thing, not a bad thing.

The added soil also settled. This is normal. next time you mulch, I'd consider a shredded mulch. Wood chips tend to float. Also, 4 inches is quite a bit. 2-3 inches is plenty.
All that being said, I agree with the poster above. Most plants will come up, just keep an eye out in the Spring.

I don't think you have huge worries, but I am going to offer a differing opinion. I would not recommend burying the crown of many perennials with a thick layer of mulch. While most perennials (and bulbs) will easily push up through the mulch in spring, I can think of a good many perennials - typically those that maintain basal foliage throughout the winter - that will resent a heavy, winter wet topdressing over their crowns. It has a tendency to promote rot and encourage fungal problems. And while wood chips make an excellent mulch for trees and shrubs, I find them far less desirable for perennial plantings. Wood products require nitrogen-utilizing soil organisms to break down - mulching with wood chips will create a nitrogen deficiency at the soil surface. While this is not a problem for stronger, more deeply rooted plants like trees and shrubs, it can be an issue for the fine, shallow root systems common to perennials and annuals.

Having cautioned about potential problems your wood chip mulching COULD produce, I don't think you should see any ill effect this coming spring - as your plants are so newly planted, extensive root systems have not been established and if you couldn't differentiate where the perennials were planted, there is likely no basal foliage involved. I would however apply a nitrogen-based fertilizer (alfalfa meal, bloodmeal, etc) in spring as new growth to offset any possible depletion. And avoid working the chips into the soil.

Mulch materials are purely a personal and availability preference. But I believe coarse textured, wood-based mulches have little place in a perennial planting bed. Their heavy texture tends to detract from the plantings, you have the issue of possible nitrogen depletion to contend with and they offer little in the way of soil improvement. Compost, either your own or commercially bagged (or bulk), is a far better choice. Save the wood chips for your tree and shrub plantings or for garden paths.

Perhaps I missed this in replies above, but mulch is best applied after ground freezes, especially in the case of unestablished plantings. Freeze thaw cycles tend to heave new plantings from their accommodations, exposing roots to winter winds & dessication. Mulching after ground freezes helps prevent freeze/thaw by helping to keep the ground frozen.

Al