The fact that you are aware that you feel this way is valuable information and most certainly something to discuss with T, regardless of whether or not you actually join the group at the same time as someone else.

Also, I wanted to mention, in response to optimize's post, that it's not necessarily true that each client is given a chance to talk about their issues in group or that newcomers get "dibs". I'd imagine that it largely depends on the person and the type of group..and it's not the case with the group therapy that I'm involved in.