So today I encountered something strange on my game. I went to give Wada a fish and he said "too many gifts" thing is, I didn't give him anything today. It was a Tuesday and it was the Snowman Festival. It was strange, but I hope it doesn't mess up my game because I still don't have his sunstone.
Wada tends to show up in Shea's house after festivals, even on days he wouldn't normally visit the islands. Since it's not one of his normal visiting days, he'll behave as if you've already talked to and gifted him that day. He should return to normal on Wednesday.