ESP8266 3.3V and ADAFRUIT TRINKET 5V I2C communication
Short Answer:
Looks definitely Okay  



Long answer:  

Here is the reference design or solution for the similar case from NXP:
https://www.nxp.com/docs/en/application-note/AN10441.pdf  





One option was to look for the high voltage tolerant I2C Pins. Normally, in most of the MCUs you can find that information. The I2C pins will be tolerant to higher voltage than the VDD of the system. Example: STM32F405 MCU:   

 In your case, I could not find the related information in the datasheet. 



Looking into the datasheet of the part 5LN01SP:  




The maximum gate threshold voltage is 1.3 V (we have a good buffer of 3.3 V - 1.3 V = 2V)  
Forward voltage drop of the body diode is 0.85 V typical (1.2 V maximum), still we have guaranteed buffer 2.1 V (3.3 V - 1.2 V).    
The series resistance hardly matters if this is the only device on the I2C bus.   
at 100 Hz or even a few 10s of KHz of clock frequency, I do not expect any problems as such.