SOs family and money.

So my SO and I have been together for 3 years and we are ttc.

His grandma decided she'd give us a check of $600 for Christmas and my SO father was supposed to drop it off.

Now he came by today, dropped off a new cage for our ferrets he got for free, used the bathroom and left.

Didn't drop the check off it seemed.

So I sent my SO a message asking him to remind his dad to drop it off next time they swing down or make plans for us to come pick it up and hang out.

Well before I got a response from my SO I go to clean the bathroom and find the check taped to the bottom of the toilet seat.

I send a picture to my SO and he said, "Yeah dad just messaged me he'd tell me where it is when I got home or it wouldn't be hard for me to find."

I'm furious.

Am I really so untrustworthy that he has to hide a check? Seriously?

Is this normal behavior for anyone else? How did you handle it?

How should I handle it?