Man...I've looked through all sorts of stuff online, and still nothing to help..
You're not really a "n00b" to this...so I don't want to dissmiss this as a simple "newby panicking over green beer" issue
2 questions....
What hops went into the amber you cooked on the old cake? Did you use any of the grapefruity hops in that batch?
You do know that you should always go darker when you pitch onto a yeast cake, right? That way you can mask any lingering flavors...For example I pitchet a brown ale onto my amber ales cake....
And it looks like you went lighter onto the cake with all that pilsen malt, that may be the issue....
Do you have any of the washed yeast cake left over? If so take a sniff and see if has the grapefuity smell to it...if you're gutsy enough, take a taste.....
If it's that...then you know to use it for darker beers like your upcoming pirate stout brew.