Wifi Re-Connect issues

Hey,

I am lucky enough to live in Uganda,where power is known for being so "reliable"! most nights we have a power cut for a few hours in the early hours.

My iMac is linked to a UPS which keeps it on through out the power cut, but my Airport Express cuts off (as that isnt on a UPS and also cannot be) I have noticed, that since I have upgraded to 10.8.3, when I get up in the morning the iMac isn't connected to a Wifi, this is a bit of a pain as the internets so slow i tend to download over night! has any one else had this problem since they got 10.8.3 or is it me being stupid, (also noticed same issue on MacBook Pro)

Cheers
Rich