Probably has a little bit of grease dragging between wheel bearing and freehub bearing.
What brand hub?

It just means there is more friction in your freewheel than in the rest of the drivetrain (chain, jockeys, bottom bracket). This is pretty good as long as you aren’t concerned about minimised friction while coasting. If you’re pedaling it’s not a problem.

Just a tiny bit more drag, which will be from either the new seals in tue bearings, or the newer grease in there that us still a little bit thicker than grease thst has been in use for a bit.

Hop on the trainer and run speed up to about 20 mph and the coast while watching the chain. If the top chain drops down to the chain stay, you have a problem with too much drag. You don’t want to ride outside like this because if you stop pedaling the chain can get thrown into the wheel.

The drivetrain moving while spinning the wheel is a good indicator of low friction, which you want. Excessive drag of the free hub is not good.

Excellent, this is all good. The wheels are Giant SLR - 0 Aero 55s. Don't know what bearing the shop replaced it with because I didn't think to ask but as long as the consensus seems to be that this is not a problem (provided it's not excessive) then I'm happy.

Often times the seal between the freehub and hubshell, if there is one, has to be seated. when it’s seated properly there’s no contact between the freehub and the hubshell and there’s no freewheeling drag. I’m not familiar with Giant wheels but it might be worth checking if this is the issue.

Could be several things:

-New bearings not installed properly (i.e. misaligned, overloaded, etc). Or if the hub has adjustable preload - they just adjusted it wrong.
-They forgot to install a necessary shim or hub part during reassembly.
-The new bearings are normal and just need some break-in (i.e. the standard seals are tight-ish)
-They used a bearing that's specifically built for being weatherproof. Phil Wood has a line of bearings with SUPER tight seals and thick grease (I think the seals are orange, where their "normal" bearings have black seals). I used to use these on the old Zipp 182 hub, which had tiny size bearings that wouldn't last me more than 4-6 months for normal training in all conditions (the rear bearings, that is).
-They used the wrong spec of bearing (i.e. used a radial style when an angular contact was the proper spec).

 
Silly one but do you have a spoke protector on the wheel? If so it may be that it isn't properly connected to the spokes and is creating drag which is easy to adjust back into place with a thin screwdriver. If it isn't that then the shop needs to relook at it. Something is too tight and needs to be readjusted or reinstalled.

No spoke protector.

Regardless, just to be safe, I will bring these into the shop and ask them to take a quick look