Hi guys!
Thank you both!
The relay was working fine, drawing roughly 3.5 mA from the ESP.
I was curious to try PieterP's suggestion and add a second 150 ohm resistor in series with the module.
It still works great, and current has gone down to 1.65mA!
So I guess I'll stick with the resistor. Any disadvantages? (apart from extra cost and breadboard space?)
Thanks!
Marc