I generally disagree here. While I think it is in your best interest to have the most up to date grades possible, I was actually advised against sending in my spring grades for the sole reason that my committee letter began writing prior to spring grades coming out. I was than told that leaving spring grades out leaves room for a great follow up letter. AMCAS doesn't specify specifically and therefore I'm not sure it matters. There are a million other forum posts that suggest resend if they make a BIG difference, or don't waste your time. Personally I sent them in as of May 5th the day the applications opened because I was anxious and I knew full well my spring grades wouldn't be issued by than.
As luck would have it, sitting here today waiting for my personal statement to have its final revision I've yet to submit. I'm not worried and all the literature I can find again simply states, submit if it benefits you, else don't worry about it. Are you hiding grades? Perhaps one might find a reason to think that, but in reality if you have 3 years of studies to back up strong grades there is no reason to think otherwise. Just list the courses as future/current. I plan to also list my fall and summer semesters as future/current as well.
Logistics was also an issue for me I might add, I have to hand deliver transcript request forms when sending to AMCAS as per a school policy and I was not present at my school to be able to do that -- no post dating was allowed either.