what to do?

Today I was at the mall, while there I let Colson play in the play area for a while to get some energy out. As we were preparing to leave, Colson stood up on the bench seating that surrounds the play area and as he did, he accidently knocked over a cup of coffee a guy had sitting on the ledge and it spilled all over some Brand New clothes his wife had just bought and was arranging in a box on the other side of this bench! Well, they were very nice about it and Colson obviously felt very bad about it. (He hung his head low and wanted to hide in Mommy.) I apologized several times and went ahead and left... I felt horrible and wanted to do something to help fix the problem my son Accidently caused, but what? But, on the flip side, I felt the man was partially to blame. He had his coffee sitting on the edge of the bench which was curved, not a level ledge, and my gosh it was the bench of a children's play area! Hello, accident waiting to happen! So, part of me was thinking he should have known better than to place it there.

My question is, "What could I have done, if anything, to repay them for damage done?" Or better said, "What would have been the right thing to do, as the mom, in this situation?"

Yes, it was an accident, but I kept thinking...Those were Brand New clothes, possibly a gift for someone because she was putting them in a box. Could she return them to the store and get a refund? If they were a gift and the store wouldn't accept them, she would have to take them home very soon, remove the tags and wash them to avoid staining and what kind of a gift would that be?

I guess I'm still feeling bad and thought I should have done something, I just didn't know what to do.

So, if you have any thoughts on this, I'd love to hear it.