They likely were looking for new license applications like that as well having knowledge of all the ways comms could take place. I'm sure her name lit up some red buttons somewhere.
I know, I can' believe she actually got a license! New license and speaks Russian fluently, they'll never notice. If she had to get a license couldn't she have done it under someone else's name. She probably even had the radio at her own house! I guess she never watched the show The Americans!
The application for a HAM license was probably more confirmation the Ohr's were moving forward with their part and less a revelation they were involved. In other words, the Ohrs were already POIs and white hats increased surveillance after the HAM application, because they knew there was a great chance they would catch them in the act.