How i must react on this?

I'm 15 y.o. guy, somedays ago,we hangin' out in one of my friends house,i mean it was 6 guys there when his mom came to us to talk, really she is like friend for us,when i was about to get up to make her room for sit down,she put her hand on my shoulder, said ''don't get up,sweetie'', and sat on my lap, really nothing was happened, she just sat on my lap and talked with us for about half an hour,then she pecked me in cheek, said ''thanks for comfy seat'' and go out.