xygmum,

first of all, sorry for the loss of Savannah (beautiful name!) and congratulations on your healthy baby girl..

i don't think that you have any reason to be concerned. my SIL's OB gets all of her patients to have 34wk scans just "to be safe rather than sorry". so given that Savannah had health problems, your OB probably just wants to be as sure as possible that they haven't missed anything in your current pregnancy. i don't think it would have anything to do with measuring big for dates, because those measurements are notoriously inaccurate anyway (i think my OB just takes them to make sure that i'm getting gradually bigger, but doesn't really care what the actual measurement is - as long as it's bigger than last time iykwim?)...

if you're still concerned, just call your dr back and ask him/her why they have recommended the scan, and explain your concerns to them - i'm sure they'll be happy to go into more details for you...

please don't worry, i'm sure everything will be fine, and you'll be blown away by the scan - your baby will be so much bigger than the last time you saw her!! almost fully-cooked!