liaison with j'étais allé

Myrna, 

yes, it is an optional liaison. 

Although I regularly hear liaison with ‘ je suis ..’, in everyday speech I can’t recall hearing anyone use the liaison after ‘ j’étais…’. 

It is optional and most, but not all, spoken French I hear is ‘from the East’ so could be regional, but my impression is that it is one of those optional liaisons not frequently used nowadays in everyday spoken French. 

https://www.lawlessfrench.com/pronunciation/optional-liaisons/