when is api gateway overkill for microservices?

So, my team is pretty small, but we're moving towards microservices and now people are talking about an API Gateway. Honestly, it feels like way too much overhead for where we are right now, especially since most calls are just internal service to internal service. Are there times when a full API Gateway pattern is just overkill? Maybe simpler direct service-to-service communication or something a bit lighter would work better? I'm really wondering about the trade-offs here, and when you all decided it was time to actually implement a gateway.