idk if what my mums boyfriend did was inappropriate

So when i was about 10 my mum got a new boyfriend who we moved in with. Not long after this (I can’t remember if it was me who wanted to do it or not) but we (me and my mums boyfriend )would kiss each other just like a peck on the lips. I kissed my mum all the time as an act of love like when saying goodnight or I love you so i never thought kissing him was weird. Now i am 18 and i look back and wonder if it was actually weird or if it was harmless. My mum was aware and was present most of the time when it would take place and she never said anything or tried to stop it. What do you think?