Sorry I wasn't around last night, but I was playing bridge.
You don't say where you are, and that could affect the answer, as Alert regs vary geographically. In the ACBL, I don't believe this 1NT response is alertable. If you are in some other jurisdiction, let us know where and we'll try to find an answer for you.
You might ask the TD to show you the part of the Alert Regulation that says this call is alertable.