Consistency often carries important meaning in therapy, relating to issues of trust. I guess the question is to what degree does her inconsistency undermine your trust either in her as a T, in the relationship, or in your ability to progress?

If it's nothing more than a minor annoyance, maybe you can work through it. If it feels like a bigger issue, do you think you can work through it?

Did she explain her 4 month break? Did she prepare you for it? Offer any interim arrangements?