Very interesting hun, there COULD be logical eplanations for it all but to be honest i think it's nice thinking it's your dad.
It's also nice of your DP to ask those questions, my DP would have freaked and smashed the toy into a million pieces

I think you need to go with your gut on this, what do YOU feel it is?
If it happens again in your presence can YOU do some asking, maybe one day when your home alone you could just sit down, relax and ask for a sign (don't be disheartened though if you don't get it) - see what happens?

I think it's beautiful though if it is your dad, that he has found a way to make a connection.