Is it being held in Spain? Under status, does it say "Package in Transit"? If so, you are probably ok.
When I sent cash, it said it was being held in customs in Canada. It was held at custom for 6 days. Then it was held at customs in Madrid Spain for 3 more days. It finally arrived at Ace. I can't say 100% your ok, but be patient, sometimes it just takes time to process things. Besides, Spain probably could care less if there are seeds being shipped out, it's coming into the U.S. you have to worry about.
Peace, God bless
They should say, "processing through customs", instead of, "held in customs." Recently tracked payment and that "held" status, especially after a few days, had me thinking my cash was lost. But it cleared.
First time I have tracked a payment for beans and probably the last. I'll just go back to waiting for the call saying I have a package to pick up. It's worked fine for years. I went and got all worked up when there was no reason to. No more peeking for me.