My First Massage From My Son

I'm a mother (42)of three sons teenager, and today after making housework I was very tired, at the end i just relaxed lying down on the sofa, and after some time my biggest son sit down next to me, the other two where out in the garden and he ask me first if i want something to drink, and next to give me a glass of water he ask me if i want a massage at the shoulder, he said he see i have do a lot of housework and he's bored, i agreed with him and sincerely is the first time one of my son ask me something like this, normally when i do housework i'm wearing a long shirt with only panties, i haven't a lot of breast and i normally not wear bra, i was lying belly down and my son take to massage me on my shoulder and at first i think was very weird, next i'm going to relax a lot and i enjoed the situation, after some time i was very relaxed and he ask me if he could get on my legs to continue massaging my back, i said yes if that was better for him, next i think was really strange and weird, with him over my legs near my ass, he massage me a lot and sincerely i get a little horny, i don't know that to think about this, but i'm super shy person and to be touched like that by my son made me so confused, at the end of the story i finish with my nipple very hard and with him leaning against my ass (i think with a hard penis) after like an hour the other two came home and thanked him and i went in the kitchen.