Thanks fellas,
Todd: All double sided tapes will yellow over time I know this from previously working in the upholstery industry where we used double sided tape daily on fabrics. Every time we had a job come back from years previous the tapes had severely yellowed and these were the best quality tapes on the market.
I actually didn't use any tape to stick this one down the bubble came from a repro card, when I removed the original tape ( which had yellowed ) the sticky residue left behind was enough to re-stick it to my custom card. In the future i'll be using a spray adhesive and applying it with a cotton bud as I've never know this stuff to yellow and it dries almost 100% clear. Beauty of using this method is you can apply it thinly enough that it is hardly visible.
3M's range of spray adhesives are the best in my experience.
Ryan