Roofing, Gutters and Waterproofing - ridge vent installation advice

The roofers installed a ridge vent over the underlayment (tar paper) for the shingles. It's not really tarpaper but a fibrous / poly sheet. Is this proper? I thought there should be a clear gap underneath the vent for proper ventalation. Thanks for the advice.

Not a roofer, but the ones I've seen you could look straight into the attic before the vent is put in place.

Now, they may have used something like a mesh that is designed to allow airflow, but help preclude any wind blown rain from penetrating. I seem to recall seeing something like that.
It wouldn't have been used over the entire roof though.

Like GG said, they should have cut down on your roof about 3" on each side under where the ridgevent is to go. They may very well use a mesh underlayment then the ridge vent. They should run their shingles right up and under the lip of the ridge vent and cover the ridge vent with ridge shingles to match your house. If you have access to the attic near where the ridge is, go up there and look up. You should see the air space they cut for the ridge vent. If they just put a ridge vent over your peak, call them back out and have them do it right.

There is a gap but it's no where close to 3" it's more like 1" on each side at the most. They also left the shingle underlayment (sort of like a spunbound material) over the opening. Apparently they were short some shingles so they have to comback and complete the job.