What would you do?

I work as a nanny for a family of two boys, 2 and 5 years old. I've only been working with the family for a couple of months but in the past few weeks the older son has been saying things that make me a little uncomfortable. He started with telling me he loves me and that he wants to marry me which was cute but today while we were coloring he asked me to draw us having a baby and later after I had changed the subject asked me to draw us sleeping together in a hotel room. I know this is a kid and it's completely innocent and he most likely has no idea what he's talking about, but I am just not sure what to do whenever he starts talking like that. He's becoming really persistent with it and it's a little annoying but I'm mostly just debating whether or not I should bring it up to the mom and ask her how she would like me to handle it.