I started on 15mgs of Pred in July and have tapered to 9mgs. It didn't start immediately but after a while I began to find the lower half of my head and nape of neck gets very sweaty, usually mid afternoon. It doesn't even have to be hot, the slightest exertion or anxiety will bring it on. It usually only occurs once daily but can be quite embarrassing, especially if it also drips!
Consider yourself lucky that it only happens once a day. Prednisone makes you have hot flashes. I get them all day long, every day. I hate it. I sit in front of a fan all day long. I use an ice bag behind my neck to help cool me off.