Mug Sub - Dye leakage outside transfer area

Hi (and my first post),

We do dye sublimation onto mugs using silicone wraps and a convection oven. Have been doing this for a few years now.

Most problems we've been able to solve over the years but one that seems to pop up intermittedly is doing so again. To wit:

I'm getting a light ghosting outside the transfer area of the mug (near the handle where you obviously can't put a transfer). It looks like the dying is leaking from under the transfer. We can make the problem go away by taping the entire transfer top to bottom so it doesn't have anywhere to leak but this is time consuming.

I've tried different times, temps (although not a lot), different lots of sub paper and probably sub dye. The problem seems environmental (and yes, we're getting a barometer thingie to try that problem out).

Has anybody out there experienced this and know why it happens?

any help is greatly appreciated.

thanks,
Frank