Yep, my guess right now is that things are getting really busy now at Tesla since it's Summer time and people know they have to get it by the end of June for the Federal Rebate. If it were me, I wouldn't risk the possibility of missing out on $1,850 unless what you are assigned is unacceptable (super high mileage with no discount, really old build with no discount, etc).
If Tesla is competent (which I'm not completely sure of in terms of delivery), they will make sure that every "lost" Model 3 is shipped out to SOMEONE and close on as many orders as possible. I can't speak for others, but if I'm told that my M3 won't be available for pickup till after June 1st, I'm cancelling the order and will just wait a year or two until prices on used ones decrease. I don't have any state rebates, so a $1,850 rebate isn't enough for me to pay this type of dough. I need the full $3750 to justify purchasing it.