Is it normal that i sometimes feel like my mum wants to try me ?

My parents divorced some years ago. I live with my mum. She is 38 and a stunning lady, she has a beautiful body and face. If she wouldn't be my mom... hmm.. All my friends told me ''what would they do to her :D'' And well, anyways, she sometimes goes out with her guy (more a sex toy than love i think), you know, to have ''some good time together''. I wish best for her, so i tell her, that i don't mind if she would go out with 10 guys, just that she gets as much fun as she wants, and so on. We are really opened to each other. We often talk about sex without any embarrasment. She knows what lenght is my cock, she isn't bothered if she runs down the hallway naked to her room, and i see her.. She just jiggles a bit, and i smile, and it's ok. When she comes home from a date, she always tells me how it was, (not too in details though), like ''i did something special for him this time...'' and licks her juicy lips and gives me a dirty, naughty look. Some time ago, she asked me if i would take naked pictures of her for her guy... And, i didn't think for long, i said yes. Then she said...''mmm... i don't know... well.. maybe not naked.. i'll see !''. And we didn't talk of it from then on. When we are on vacation, i put suncream on the back of her naked body; in the front she does it alone. then, sometimes she takes off her bra on the beach, and she asks me if her tits look better than ''that girl's'', and so on.. When she goes out with her guy, she comes to me first with her sexy underwear, sometimes corset and so on, and asks me if i like it, if it will work. And we laugh, then she goes . But once, i was on my computer, checking the internet, and she came in, and said ''good night, honey'' and gave me a kiss on my cheek like always. And i didn't even looked at her.. Then i noticed, she didn't backed off, but she started to gently lick my neck, and she was kissing and licking my neck for the next 3 minutes ! i was hard as a rock, what can i say ! i liked it VERY much, i'm a guy after all... but now i think, she was just checking, if i would go for it, then she would be dissappointed, i think it was that. Because when i asked her something real, like ''if she did gave him a blowjob'' or anything; she just blushed, smiled, gave me that naughty look and didn't replied... so i think it was that.. what do you think ? is it normal ?