Good customer service or bad form?

I'm on my second Goodreads giveaway and with a only few days left before decision-making time, I'd like to "poll the audience." 
Goodreads provides the host of a giveaway with the names and addresses of the persons who win.  The host then ships off the books as promised.  However, Goodreads strongly discourages said host from directly contacting said winners.  Through Goodreads, I mean.  Last time, I did anyway.  Here's why.
I had tracking numbers for the packages!  The tracking numbers were of only mild interest to me; I got them for the express purpose of providing them to the winners so that they could see what was going on.  I could've put them in the packages themselves, but although they would've been delivered to the winners without my contacting them through Goodreads, I think we can all agree that it would've been worse than useless. 
Neither winner complained (to me) that I contacted them directly.  Neither winner responded (to me) at all, in fact.  So I'm left wondering - is contacting a giveaway winner once, with a tracking number (something pertinent and useful) good customer service? or bad form?
Thanks for your input!