Possible bug on sms.available

Hi , i'm testing the receive of sms message within the sample sketch receivesms provided by arduino
if i left powered on all the time the mkrgsm everythings is fine but when i add deepsleep , sms available is no more evaluated...if i send a message from my phone when mkr is in deepsleep , even if i wait 1 minute when checking sms presence , everytime it return no message.
if i load the gsmpassthrough and i use the ublox utility to connect to the modem i can see the message in the modem memory....
i have attached my sample sketch

ReceiveSMS.ino (2.91 KB)

When I go into sleep, I disconnect from the GSM/GPRS networks. I do not see where you do this on sleep call. For example I perform "gprs.detachGPRS();" and then "gsmAccess.shutdown()" before I call the sleep function. When it comes back up it will find all of the new texts.