Likewise here in Maryland, they were active last year on my 3 years old cane prune/SVP vines. The damage was not at a volume that was alarming, just a PIA for the occasional shoot they would saw.
Invariably the sawn shoot would throw out a lateral below the cut, and after some regrowth I would retie the shoot-- with upward growth continuing just fine, if mis-shapen. I noticed in March during pruning that some of those shoots ended up as a fruiting cane on some of this years vines and seem none the worse for wear.
To confirm that is the grape cane girdler, keep an eye out for small black beetle-like bugs, about 2 or 3 mm long. I did not spray against them last year and hope to avoid it again this year. From what I've read, they mainly hit young grapevines. Some suggest that 10% damage is considered a threshold for doing a spray.