Update a multiple select field using Airtable API

[RHB]

I have a kanban view with 5 columns, day 1 through day 5, for following up with leads. I want to fire off a text message using salesmsg through zapier each time the lead is dragged into the next day column. 

The issue I'm having is in zapier, it seems that every time I update the lead, regardless of the field, the sms is triggering, sending the message multiple times whereas I just need it to send once.

Any help is greatly appreciated!