My 3 year old cousin likes to rest his hand or head on my "bosom" (specifically; not my chest and I know it's intentional). I try not to make too big of a deal about it (to avoid drawing attention to negative behaviors and tempting him to do them more) so i'll often simply redirect his hand to a more appropriate place (higher on the chest or my shoulder). A quick google search suggests that this is age appropriate and that toddlers begin to become more aware of things like that in this stage. However, i'm still not sure if I find the behavior inappropriate or age appropriate or how to deal with it.

He only watches cartoons and is only around his mother, father, me and his grandmother all day so I'm 99 (really 100%) sure that he's not being abused or anything and is a happy, healthy, veeeery active but also emotionally sensitive boy. I'm not sure if I am projecting my own issues onto him and am just hyperaware of it because it makes me feel weird when he does it because he and I are super close and I don't want to be sending the wrong signals to him unintentionally.