Why is NetSuite assigning an Invoice Number when you edit a Memorized Transaction?

Part of our business runs on NetSuite and the rest of our business runs on Microsoft CRM/GP.  For accounting purposes, we have a sort of loose integration between NetSuite and Great Plains.  It's based on querying NetSuite using smbXML, taking the resulting output file, and importing that file into Great Plains.  Since the v2008 upgrade, we've noticed that memorized transactions having been getting into our invoice output files and throwing off our results.  To try to figure out what had changed in NetSuite, I queried our NetSuite accounting folks, who responded with this:

I noticed in January that Netsuite would give a memorized transaction an invoice number, but it would only do this when I was editing it, and it would go away as soon as everything was saved.  Now, I am noticing when you open a memorized transaction just to look at it (and edit it as well), it assigns an invoice number to it, which is bizarre, because it will still say “memorized transaction” across the top, so Netsuite is recognizing that this isn’t a valid invoice, but yet is still (temporarily) assigning a number to it.  However, if you are