Is measurement of 1.5 x 1.1 x 0.4 cm for cervical lymph node concerning? was told it had moderately thickened cortex and most likely reactive. was sick ~2-3 weeks ago and bloodwork came back showing i likely had ebv at some point in the past 6 month?

Typical for a reactive lymph node specifically in the context of recent EBV infection, majority of lymph nodes melt away slowly, some may remain slightly enlarged indefinitely.

Reactive lymph node by ultrasound is a benign finding for a mildly enlarged cervical lymph node. You should not worry much, recheck the node every 2-3 weeks then you can ignore it if size does not change or it gets smaller later on. If the node gets bigger or new node appears, you should see your doctor again.

You may feel the nodes every couple of weeks, if any of the lymph glands doubles in size, becomes painful, ulcerates, or other nodes become enlarged, or you develop fever, or lose weight, you should see a doctor. Wish you good health!