Tips on getting glue off stained glass?

[TheNibbler]

We just got a new front door and it has a piece of stained glass in it. When we were treating it with wood oil we covered the edge of the glass with masking tape. When we took the tape off there was some residual glue left on the glass. Any ideas on what would be the best way to get this off while avoiding getting any water/other liquid on the wood that surrounds the stained glass?

Thanks