It definitely does a little bit! Given the academic calendar I'm not entirely sure how worrying it might really be; it's a good time maybe to remember that people are always entering and leaving participation in different communities.
At any rate, I think it might be worth considering outreach efforts particularly in the summer; both to get members more deeply engaged in the community so they're likely to stay plugged-in even in the absence of a structured academic environment; and on the other hand to capture more incoming students' attention, if only to let them know that we are available as a resource.